The Masu Form (ます): Polite Present and Future Tense

The masu form is the polite present and future shape of a Japanese verb. It is made by attaching the auxiliary ます to a verb's stem, and it is the first conjugation taught in nearly every elementary curriculum.¹² It is the default polite (丁寧体) register for adults outside close-knit groups. It covers both present and future readings, and it unlocks a whole family of related grammar through the stem left behind when ます is stripped off.³⁴

Overview

What the masu form is

The masu form is the polite affirmative non-past form of a verb. It covers both present and future readings.¹² The label 丁寧形 ("polite form") applies to the verb in this slot. The broader 丁寧体 ("desu/masu style") is the register defined by this form together with the polite copula です.⁴⁵

Morphologically, the masu form is the verb's 連用形 (ren'yōkei, masu-stem) plus the polite auxiliary 助動詞 ます.³⁶ In other words, it is stem + ます. Removing ます leaves the bare stem (書き, 食べ, し, 来), which is itself a paradigm slot, not the polite form.³⁶

私わたしは毎日まいにち日本語にほんごを勉強べんきょうします。¹
"I study Japanese every day."

田中たなかさんは銀行ぎんこうで働はたらきます。²
"Mr. Tanaka works at a bank."

ます is itself a conjugating auxiliary

ます is classified as a 助動詞 (auxiliary verb) in school grammar and has its own paradigm: 未然形 ませ / ましょ, 連用形 まし, 終止形 ます, 連体形 ます, 仮定形 ますれ, 命令形 ませ・まし.⁶ The cells of the polite paradigm (ます, ません, ました, ませんでした) are conjugations of ます itself, attached to one fixed stem on the host verb.³⁶

Register and JLPT placement

ます is the default polite register taught first because it is socially safe across the widest range of beginner contexts: strangers, customers, teachers, and classmates of unknown standing.⁷⁸ It is taught before the plain form in nearly every major elementary curriculum (Genki Lesson 3 vs. Lesson 8; Minna no Nihongo Lesson 6 vs. Lesson 20). The reason is practical: accidentally using plain form with a higher-status interlocutor is riskier than sounding overly polite among peers.¹²

ます is 丁寧語, not 尊敬語 (honorific) and not 謙譲語 (humble). It politely points to the addressee; it does not raise the subject or lower the speaker.⁵ The 文化庁 (Agency for Cultural Affairs) 敬語の指針 (2007) places 丁寧語 (the ます / です layer) as one of five categories of 敬語, structurally separate from the honorific and humble categories taught at N3 and above.⁵

Frequency data from the BCCWJ (Balanced Corpus of Contemporary Written Japanese) shows the desu/masu style dominating public-facing prose (instruction manuals, public notices, customer-service text). The da style dominates newspapers, academic writing, and most novel narration.⁹⁸

はじめまして、田中たなかと申もうします。²
"Nice to meet you. My name is Tanaka."

Present and future in one form

Japanese has no separate future tense. The non-past slot, here the masu form, covers present-habitual, generic, and planned-future readings. Tense is read from context.¹⁰¹¹ 食べます can mean "eats" (habitual), "is going to eat" (planned), or "will eat" (future), depending on time adverbials and discourse context.³¹⁰

毎朝まいあさコーヒーを飲のみます。¹
"I drink coffee every morning."

明日あした友達ともだちに会あいます。²
"I will meet a friend tomorrow."

来週らいしゅう京都きょうとへ行いきます。¹
"I will go to Kyoto next week."

Formation rules by verb group

The masu form is built by selecting the verb's 連用形 (i-form stem) and attaching ます. The procedure differs by verb group. First identify the group, then apply the matching rule. The group splits are covered in the Japanese Verb Groups article.

一段 (ichidan / ru-verbs): drop る, add ます

For a 一段 verb, remove the final る and attach ます directly.³¹²¹³ The ichidan stem is the dictionary form minus る. The masu form is that stem plus ます.³¹²

Worked: 食べる → 食べます, 見る → 見ます, 起きる → 起きます, 寝る → 寝ます, 教える → 教えます, 始める → 始めます.¹¹²

朝あさ七時しちじに起おきます。¹
"I get up at seven in the morning."

夜よる十一時じゅういちじに寝ねます。²
"I go to bed at eleven at night."

毎日まいにち野菜やさいを食たべます。¹
"I eat vegetables every day."

五段 (godan / u-verbs): shift the final u-row kana to i-row, add ます

For a 五段 verb, the dictionary form's final u-row kana shifts to the same column's i-row kana (the 連用形 / i-form reflex). Then ます attaches to that stem.³¹¹¹²

Column by column: く → き, ぐ → ぎ, す → し, つ → ち, ぬ → に, ぶ → び, む → み, る → り, う → い.¹¹¹²

Dictionary	Stem (連用形)	Masu form
書く	書き	書きます
泳ぐ	泳ぎ	泳ぎます
話す	話し	話します
待つ	待ち	待ちます
死ぬ	死に	死にます
遊ぶ	遊び	遊びます
読む	読み	読みます
走る	走り	走ります
買う	買い	買います

Reconstructed from the worked lists in ¹, ², ¹¹, ¹².

う-verbs shift to い, not わ

For 買う, the masu form is 買います, attached to the 連用形 stem 買い (い). It is not ※買わます (attached to 買わ-, the 未然形). The 未然形 in 買わ- appears only in negative-plain (買わない) and volitional-plain (買おう) forms. Learners who memorise the negative-plain "shift to a-row" rule and re-apply it under ます produce the wrong form.³¹¹

図書館としょかんで本ほんを読よみます。²
"I read books at the library."

公園こうえんで子こどもと遊あそびます。¹
"I play with my child at the park."

駅えきで友達ともだちを待まちます。²
"I will wait for my friend at the station."

スーパーで牛乳ぎゅうにゅうを買かいます。¹
"I buy milk at the supermarket."

Irregular verbs: する → します, 来る → 来ます (きます)

The two true irregulars in modern Japanese both have an irregular 連用形.³¹¹ する takes the stem し: します.¹¹² 来る (くる) takes the stem 来 read き: 来ます (きます).¹¹²

The reading shift for 来 is worth memorising on its own. The dictionary form 来る reads くる. The 連用形 reads き. The 未然形 reads こ (来ない / こない). The same kanji takes three different readings across the paradigm.¹¹⁶

する-compounds (Sino-Japanese noun + する) follow する: 勉強する → 勉強します, 電話する → 電話します, 結婚する → 結婚します, 運動する → 運動します.¹²

毎日まいにち日本語にほんごを勉強べんきょうします。¹
"I study Japanese every day."

田中たなかさんが八時はちじに来きます。²
"Mr. Tanaka is coming at eight."

後あとで母ははに電話でんわします。²
"I will call my mother later."

A unified quick-reference table

Group	Verb	Stem (連用形)	Masu form
一段	食べる	食べ	食べます
一段	見る	見	見ます
一段	起きる	起き	起きます
五段 (く)	書く	書き	書きます
五段 (ぐ)	泳ぐ	泳ぎ	泳ぎます
五段 (す)	話す	話し	話します
五段 (つ)	待つ	待ち	待ちます
五段 (ぬ)	死ぬ	死に	死にます
五段 (ぶ)	遊ぶ	遊び	遊びます
五段 (む)	読む	読み	読みます
五段 (る)	走る	走り	走ります
五段 (う)	買う	買い	買います
不規則	する	し	します
不規則	来る (くる)	来 (き)	来ます (きます)

Reconstructed from the per-group rule statements and worked lists in ³, ¹, ², ¹¹, ¹².

The full paradigm: ます, ません, ました, ませんでした

The four polite cells are conjugations of the auxiliary ます attached to the same fixed stem. Once you know the stem, all four cells follow mechanically.

Affirmative non-past: 〜ます

This is the base cell of the paradigm: non-past polite, covering present habitual, generic, and planned future.³¹²

Worked: 食べます, 行きます, します, 来ます (きます).¹²

毎週まいしゅう日曜日にちようびに映画えいがを見みます。¹
"I watch a movie every Sunday."

Negative non-past: 〜ません

Drop ます, attach ません.³¹² Worked: 食べません, 行きません, しません, 来ません (きません).¹²

Historically, ません is a fused unit: the 未然形 of ます (= ませ) plus the classical negative auxiliary ぬ in its 連体形 ん, frozen as a single ending in the modern paradigm.¹⁴¹⁰⁶ The polite paradigm has no ますない cell. Treating ません as ます + ない is a category error.³¹⁰

The same negative ん appears elsewhere in modern Japanese only in fossilised set phrases (知らん, やらん). Inside the polite paradigm, ません is the only productive surviving reflex of classical ぬ.¹⁴¹⁰

お酒さけは飲のみません。¹
"I don't drink alcohol."

明日あしたは学校がっこうへ行いきません。²
"I'm not going to school tomorrow."

朝あさご飯はんを食たべません。¹
"I don't eat breakfast."

Affirmative past: 〜ました

Drop ます, attach ました.³¹² Worked: 食べました, 行きました, しました, 来ました (きました).¹²

Morphologically, ました is the 連用形 of ます (= まし) plus the past marker た. This is the same mechanism that builds the plain-form past 書いた from 書き-. In the polite paradigm, た runs through まし- rather than through the host verb's own stem.³¹⁰⁶

昨日きのう公園こうえんへ行いきました。¹
"I went to the park yesterday."

朝あさ七時しちじに起おきました。²
"I got up at seven this morning."

Negative past: 〜ませんでした

Drop ます, attach ませんでした.³¹² Worked: 食べませんでした, 行きませんでした, しませんでした, 来ませんでした (きませんでした).¹²

The form is built by appending でした (the polite past of だ / です) to the existing ません.³¹⁰¹⁵ でした supplies the past tense. ません stays unchanged because the classical negative ぬ has no past form in the polite paradigm.¹⁴¹⁰

No ※ませんかった

ません is not an い-adjective, and the polite paradigm does not run the negative through the verbal 〜なかった or adjectival 〜かった patterns. Modern Japanese uses でした as the fixed polite negative-past completer. The only correct polite negative past of 食べる is 食べませんでした.¹⁴¹⁰¹⁵

昨日きのうは何なにも食たべませんでした。¹
"I didn't eat anything yesterday."

先週せんしゅうは仕事しごとに行いきませんでした。²
"I didn't go to work last week."

その映画えいがは見みませんでした。¹
"I didn't watch that movie."

The 2×2 paradigm box

Verb (group)	Non-past affirmative	Non-past negative	Past affirmative	Past negative
食べる (一段)	食べます	食べません	食べました	食べませんでした
書く (五段)	書きます	書きません	書きました	書きませんでした
する (不規則)	します	しません	しました	しませんでした
来る (不規則)	来ます (きます)	来ません (きません)	来ました (きました)	来ませんでした (きませんでした)

Reconstructed from the paradigm tables in ³, ¹, ², ¹², ¹³, ¹⁶.

The masu-stem as a derivational base

What "drop ます" leaves you with

Removing ます from a masu form leaves the bare 連用形 (ren'yōkei, "continuative form"), traditionally called the masu-stem or i-stem.³¹¹⁶ The masu form is itself stem + ます. The slot that takes the polite auxiliary is the same slot that hosts many other suffixes.³¹¹

Worked stems from the table above: 食べ, 書き, し, 来 (き).³⁶ The stem is register-neutral. Politeness lives in ます; the stem alone carries no formality marking.³⁴

Three things the stem feeds

The masu-stem does a lot of quiet structural work. Three families of grammar attach at this slot:

1. The polite paradigm itself. ます, ません, ました, ませんでした all attach to the same stem.³⁶
2. Other suffixes on the same stem. A selection of N5–N4 attachments documented in A Dictionary of Basic Japanese Grammar:³ 〜たい (desire; 食べたい "want to eat"), 〜ながら (simultaneity; 食べながら "while eating"), 〜方 (way of doing; 食べ方 "the way of eating"), 〜やすい / 〜にくい (ease / difficulty; 読みやすい / 読みにくい), 〜すぎる (excess; 食べすぎる), 〜なさい (gentle imperative; 食べなさい).
3. Compound verbs and noun-forming use. 取り出す, 飲み始める, 書き直す (V1-stem + V2 compound); 動き, 飲み, 始め (bare-stem nouns).³

Masu-stem skips the te-form's sound changes

The te-form runs through the same 連用形 slot but adds onbin (sound-change) shifts for godan verbs: 書く → 書いて, not ※書きて. The masu-stem does not trigger those shifts: 書く → 書きます, never ※書います.³¹⁰ In other words, stem reuse stops before the te-form's onbin layer.

What this means in practice

Learning the masu form is also learning the stem. That gives learners two lessons for the price of one: the stem becomes the entry point for the N5 and N4 grammar points they will meet over the next two textbook semesters.³¹²

Nuance and usage contexts

Default in conversation with strangers, customers, teachers, and bosses

ます is the addressee-honorific default in adult interactions outside close-knit in-groups.⁷⁸ Cook (1996) documents this default in elementary-school teacher-to-student talk. Maynard (1993) documents it in customer-service, news-reading, and prose dialogue.⁷⁸

The 文化庁 (Agency for Cultural Affairs) 敬語の指針 formally describes 丁寧語 (the ます / です layer) as the politeness category that operates between speaker and addressee, regardless of subject reference.⁵ A speaker uses ます because of who is listening, not because of who the sentence is about.

いらっしゃいませ。何なにを召めし上あがりますか。⁸
"Welcome. What would you like to eat?"

Sentence-final only (in most beginner contexts)

At N5, the rule is simple: ます attaches to the final verb of a sentence. Subordinate clauses (relative clauses, most adverbial clauses, conditional antecedents) take the plain form.¹³

Tae Kim states this explicitly: "the masu-form must always come at the end of a complete sentence and never inside a modifying relative clause."¹³

The rule has principled exceptions at higher levels. Compound coordinated clauses can carry ます at each coordinated verb, and very formal speech (NHK announcements, ceremonial address) can extend ます into clauses that would otherwise take plain form.⁸ Treat that as a forward reference at N5 and stick with the sentence-final rule.

私わたしは田中たなかさんが作つくる料理りょうりが好すきです。¹³
"I like the food Mr. Tanaka makes."

The relative-clause verb 作る stays plain. Politeness appears once, at the end, via です.

Public-facing writing, announcements, customer interactions

BCCWJ shows the desu/masu style dominating instruction manuals, public notices, customer-facing service language, and most blog and how-to prose. The da style dominates newspapers, academic writing, and most novel narration.⁹⁸ NHK on-air news reading uses the desu/masu style throughout. The print news article uses da/dearu.⁸ Same content, different register, decided by channel.

次つぎは新宿しんじゅく、新宿しんじゅくです。⁸
"Next stop: Shinjuku, Shinjuku."

Where masu is wrong (or sounds odd)

Inside relative clauses at the N5 level, the plain form is required; ます is wrong there.¹³

In close peer conversation among adult equals with an established relationship, switching into ます can sound cold, distancing, or sarcastic.⁷⁸ The register is right for the wrong relationship.

In genres that conventionally take the da style (newspapers, academic papers, most fiction narration, technical reference text), ます is out of place.⁹⁸

Good to know

う-verbs attach ます to the い-stem, not the わ-stem

A common 五段 misstep is to carry the negative-plain "shift to a-row" rule (買う → 買わない) into the polite paradigm. ます selects the 連用形 (i-form), not the 未然形 (a-form). So the polite form of 買う is built on 買い, not 買わ. The wrong form ※買わます does not exist.³¹¹

毎週まいしゅうスーパーで牛乳ぎゅうにゅうを買かいます。¹
"I buy milk at the supermarket every week."

ません is one ending, not ます plus ない

The polite negative cannot be assembled as ます + ない. That pattern does not exist in the polite paradigm. ません is a single fused ending inherited from classical Japanese, with no productive decomposition in modern usage.¹⁴¹⁰⁶ The correct polite negative of 食べる is 食べません, not ※食べますない.

でした completes the polite negative past, not 〜かった

The polite negative-past is built by appending でした (the polite past of だ) after ません. ません is not an い-adjective. The verbal 〜た past does not attach to it, and the adjectival 〜かった past does not either.³¹⁰¹⁵ The correct polite negative past of 食べる is 食べませんでした, not ※食べませんかった.

来 reads き only in the masu form

The kanji 来 takes three different readings across its irregular paradigm: く in the dictionary form 来る, き in the 連用形 (来ます, 来ました), and こ in the 未然形 (来ない).¹¹⁶ The polite form is 来ます, read きます. ※来ます read くます is not a real form.

"Sentence-final ます" is the safe N5 rule

At N5 the safe rule is "ます only at the closing verb." Mid-clause ます (in a relative clause or before a subordinator) reads as either textbook-stilted or hyper-formal NHK-announcer register. The everyday spoken default puts plain forms inside clauses and reserves ます for the closing verb.⁸¹³ Treat the higher-level exceptions as a future lesson.

ます grew out of まらする, itself from 参(まゐ)らす

The modern ます grew out of a Late Middle Japanese humble-honorific construction 参(まゐ)らす ("humbly do for a superior"), shortened through まらす and まっす to ます. The older 終止形 まする survived into the early twentieth century and still appears in stylised speech.¹⁴¹⁵ This layered history explains why polite ます behaves like a small auxiliary rather than a verbal ending.

ません preserves classical ぬ inside the polite paradigm

The negative ません is the 未然形 of ます (= ませ) followed by the classical negative auxiliary ぬ in its 連体形 ん. Modern Japanese otherwise expresses verbal negation with ない, but ぬ → ん survives inside the polite paradigm as a frozen ending.¹⁴¹⁰ This explains why ません does not break down productively and why there is no ますない slot.

行く's masu form is regular even though its te-form is not

行く's te-form (行って, not ※行いて) is the standout 五段 onbin irregularity. Its masu form, by contrast, is regular: 行く → 行き → 行きます.³¹⁰ The te-form irregularity belongs to the onbin shift, which the masu-stem does not trigger. So the polite paradigm of 行く is fully predictable.

A jingle for the 五段 shift: u → i + ます

A single jingle covers the whole 五段 column shift: u-row to i-row, then ます. 飲む → 飲み → 飲みます. 書く → 書き → 書きます.¹²¹⁶ The mnemonic also makes the stem visible as a step, preparing learners for later lessons on 〜たい and 〜ながら.

する-compounds conjugate the する only

Every Sino-Japanese noun + する forms a single lexical verb whose conjugation lives on the する. 勉強する → 勉強します, never ※勉強しまする or ※勉強するます. The noun half of the compound stays unchanged. Only the する shifts.¹²

See also

• The Japanese Verb Stem (連用形): The Masu-Stem and Its Uses
• The Te-Form in Japanese: Construction Rules
• Japanese Verb Groups: 一段, 五段, and Irregular
• Polite vs. Plain Japanese: です/ます vs. だ (丁寧体・普通体)
• The Japanese Copula: です, だ, である Explained
• Keigo Grammar Overview: How to Conjugate Honorific, Humble, and Polite Verbs

References

Footnotes

1. Banno, Eri, Yoko Ikeda, Yutaka Ohno, Chikako Shinagawa, and Kyoko Tokashiki. Genki I: An Integrated Course in Elementary Japanese, 3rd ed. The Japan Times, 2020. ISBN 978-4-7890-1730-5. Lesson 3 ("Verb Conjugation: present tense polite forms"); Lessons 4–5 (past forms). ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³ ↩²⁴ ↩²⁵ ↩²⁶ ↩²⁷ ↩²⁸ ↩²⁹ ↩³⁰ ↩³¹ ↩³² ↩³³ ↩³⁴ ↩³⁵

2. 3A Corporation. 『みんなの日本語 初級I 第2版』(Minna no Nihongo Shokyū I, 2nd ed.). スリーエーネットワーク, 2012. ISBN 978-4-88319-603-4. Lesson 6 (ます / ません / ました / ませんでした); Lesson 14 (て-form; contrast with masu-stem). ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³ ↩²⁴ ↩²⁵ ↩²⁶ ↩²⁷ ↩²⁸

3. Makino, Seiichi, and Michio Tsutsui. A Dictionary of Basic Japanese Grammar. The Japan Times, 1986. ISBN 978-4-7890-0454-1. Entries on ます (pp. 235–237), the desu/masu style, and the relationship between ます and the 連用形. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³ ↩²⁴ ↩²⁵ ↩²⁶ ↩²⁷ ↩²⁸ ↩²⁹ ↩³⁰ ↩³¹

4. 庵功雄・松岡弘・中西久実子 ほか (Iori, Isao, et al.). 『初級を教える人のための日本語文法ハンドブック』. スリーエーネットワーク, 2000. ISBN 978-4-88319-148-0. Chapter on 文体 (style) and verb conjugation; treats ます as the polite-style auxiliary attached to the 連用形. ↩ ↩² ↩³

5. 文化審議会答申『敬語の指針』. 文化庁, 2007. https://www.bunka.go.jp/seisaku/bunkashingikai/kokugo/hokoku/pdf/keigo_tosin.pdf. Official guidance on the five-category 敬語 system, locating 丁寧語 (the ます / です layer) outside 尊敬語 / 謙譲語. ↩ ↩² ↩³ ↩⁴

6. ja.wikipedia.org contributors. "助動詞 ます." Wikipedia, the Free Encyclopedia (Japanese). https://ja.wikipedia.org/wiki/%E3%81%BE%E3%81%99. Paradigm of ます as a 助動詞; 未然形 ませ / ましょ, 連用形 まし, 終止形 ます, 仮定形 ますれ. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹²

7. Cook, Haruko Minegishi. "The use of the masu and plain forms in Japanese elementary school classrooms." Language in Society 25, no. 2 (1996): 187–209. Cambridge University Press. On masu as the default addressee-honorific register and its switch to plain in close-relation talk. ↩ ↩² ↩³ ↩⁴

8. Maynard, Senko K. Discourse Modality: Subjectivity, Emotion and Voice in the Japanese Language. John Benjamins, 1993. ISBN 978-90-272-5039-0. On the desu/masu vs. da style across conversation, prose, and dialogue genres. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹²

9. 国立国語研究所 (NINJAL). 『現代日本語書き言葉均衡コーパス』(BCCWJ). https://clrd.ninjal.ac.jp/bccwj/. Frequency data for the ます paradigm across written registers (newspapers, magazines, public-facing prose, blogs). ↩ ↩² ↩³

10. Martin, Samuel E. A Reference Grammar of Japanese. Yale University Press, 1975 (reprinted University of Hawaiʻi Press, 2003). Sections on the ます paradigm and the negative ません / ませんでした formation. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴

11. Tsujimura, Natsuko. An Introduction to Japanese Linguistics, 3rd ed. Wiley-Blackwell, 2014. ISBN 978-1-4051-7058-1. Chapter on verbal morphology; the i-form / continuative analysis of the godan stem. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹²

12. Hamada, Iori. Japanese Introductory 1, OER Collective (CAUL). https://oercollective.caul.edu.au/japanese/chapter/6-1/. Chapter 6.1 on the ます form, per-group rules, and worked examples. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹

13. Tae Kim. A Guide to Japanese Grammar. "Polite Form and Verb Stems." https://guidetojapanese.org/learn/grammar/polite. The masu-form attaches at sentence-final position and is not used inside a modifying relative clause in beginner-grade rules. (limitation): language-learning publisher; used for the sentence-final placement rule. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

14. Frellesvig, Bjarke. A History of the Japanese Language. Cambridge University Press, 2010. ISBN 978-0-521-65320-6. Sections on Late Middle Japanese polite auxiliaries; the development of まらする → ます; the classical negative ぬ behind modern ません. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

15. en.wiktionary.org contributors. "ます." Wiktionary, the Free Dictionary. https://en.wiktionary.org/wiki/%E3%81%BE%E3%81%99. Etymology from 参らす (mairasu) → まらす → まっす → ます; the older 終止形 まする; the irregular ませんでした. ↩ ↩² ↩³ ↩⁴

16. Tofugu. "〜ます: Verb Polite Form." https://www.tofugu.com/japanese-grammar/masu/. Per-group rule statements; the four-cell paradigm presented as ます / ました / ません / ませんでした. (limitation): language-learning publisher; used only as a corroborating beginner-grade reference. ↩ ↩²