Japanese Masu Stem Uses: One Verb Form Behind Ni Iku, Nagara, Tai, Kata and More

Finding the stem for every verb type

Ichidan verbs end in ru, and the stem is the dictionary form with ru removed: taberu gives tabe, miru gives mi, okiru gives oki. Godan verbs end in one of nine u sounds, and the stem changes that sound to its i column: nomu gives nomi, kaku gives kaki, hanasu gives hanashi, matsu gives machi, kau gives kai, yomu gives yomi, asobu gives asobi, shinu gives shini, kaeru (godan) gives kaeri.

The two irregular verbs are suru with the stem shi, and kuru with the stem ki. Every suru compound follows suru, so benkyō suru gives benkyō shi. If you already form the masu form confidently, you already know every stem; the only new step is to stop, remove masu, and look at what is left.

Purpose with ni iku, kuru and kaeru

Stem plus ni plus a verb of movement expresses the purpose of going somewhere: eiga o mi ni iku, go to see a film; tomodachi ni ai ni kuru, come to meet a friend; hirugohan o tabe ni kaeru, go home to eat lunch. The object of the purpose verb keeps its own particle, so mi takes o before it and ai takes ni.

Nouns that pair with suru can skip the verb: kaimono ni iku, sanpo ni iku, ryokō ni iku. The movement verb can be anything that moves you: iku, kuru, kaeru, deru, modoru, hairu. It does not work with verbs that are not movement, so you cannot say tabe ni suru.

Nagara, yasui and nikui, sugiru in brief

Three of the most common stem patterns each have a full guide on this blog, so here is only the shape. Stem plus nagara means while doing, with the same person doing both actions and the main action in the second clause: ongaku o kikinagara benkyō suru, study while listening to music. Stem plus yasui and nikui mean easy to and hard to, and the result is an i-adjective: yomiyasui hon, an easy book to read; wakarinikui setsumei, an explanation that is hard to follow.

Stem plus sugiru means to do too much, and the result is an ichidan verb that conjugates freely: tabesugita, I ate too much; nomisuginaide, do not drink too much. All three also attach to adjective stems, which is worth noticing: sugiru gives takasugiru, and yasui and nikui do not, but nagara can follow certain nouns such as zannen nagara.

Hajimeru, owaru, tsuzukeru and other aspect verbs

Stem plus hajimeru means to start doing: furihajimeru, start to rain; yomihajimeru, start reading. Stem plus owaru means to finish doing: yomiowaru, finish reading; tabeowaru, finish eating. Stem plus tsuzukeru means to keep doing: hashiritsuzukeru, keep running. These make ichidan or godan verbs according to the second element, so hajimeru and tsuzukeru conjugate as ichidan and owaru as godan.

Related second elements include dasu, which marks a sudden start (nakidasu, burst into tears), kakeru, being about to or halfway through (yomikakeru, start and leave unfinished), and naosu, doing again (kakinaosu, rewrite). Dasu is more abrupt than hajimeru; hajimeru is neutral and can describe a planned start.

Kata, tai and the stems that become adjectives

Stem plus kata makes a noun meaning the way of doing: tsukaikata, how to use; kakikata, how to write; ikikata, a way of life. Because the result is a noun, the object before it takes no rather than o: kanji no kakikata, not kanji o kakikata. For suru verbs, the natural form is shikata, and for a general how to, yarikata is common.

Stem plus tai makes an i-adjective meaning want to: ikitai, tabetai, kaitai. It conjugates like any i-adjective, ikitakatta, ikitakunai, ikitakute, and its object may take ga or o. Tai is only for your own wishes or direct questions to a listener; a third person's wish is tagatte iru. Stem plus sō also makes an adjective, describing how something looks about to happen: furisō, looks like rain; okisō, looks about to fall.

Compound verbs and nouns built from stems

The stem is also the glue inside compound verbs, where two verbs combine into one meaning: mochiaruku (carry around) from motsu and aruku, kakikomu (write in) from kaku and komu, hikidasu (pull out) from hiku and dasu, tobikomu (jump in), miokuru (see someone off), kikitoru (catch what is said). The first verb is always the stem; the second carries the conjugation.

Stems become nouns on their own, hanashi (a talk), yasumi (a rest, a holiday), odori (a dance), kaeri (the way home), and combine into compound nouns: nomimono (drink), tabemono (food), yomikaki (reading and writing), machiawase (meeting up), tabehōdai (all you can eat), kaimono (shopping). Recognising the stem inside these words makes hundreds of vocabulary items feel transparent.

The bare stem in formal and written Japanese

In news, reports, essays and business email, the bare stem does the job the te form does in speech: it ends one clause and moves on to the next. Kaigi ni shusseki shi, iken o nobeta means attended the meeting and gave an opinion. This is the original continuative use, and it is where the name renyōkei comes from. It sounds neutral and crisp in writing but stiff in conversation.

Two things to watch. The stem does not carry negation or tense; those come from the final verb. And in speech, the stem still appears in fixed polite expressions such as o-machi kudasai (please wait), o-kake kudasai (please sit) and o-yasumi nasai (good night), which are all o plus the stem. Once you spot that, honorific requests stop looking like separate vocabulary.

Common mistakes and how to fix them

The most common error is attaching a pattern to the wrong form: taberu ni iku, nomu nagara, iku tai. All of these need the stem: tabe ni iku, nominagara, ikitai. A second is forming godan stems with the wrong vowel: hanasu gives hanashi, not hanasi or hanase; matsu gives machi; kaeru (return) gives kaeri.

Learners also confuse the stem with the te form in formal writing, or use the bare stem in casual conversation, where it sounds like reading aloud. Keep stems for writing and te forms for talk. With kata, remember the particle switch: tsukaikata needs no before it, not o. And do not use tai for other people's wishes; tagaru or the te form of hoshii covers that.

• Stem, not dictionary form, before ni iku, nagara, tai, sugiru, kata, yasui and nikui
• Godan stems shift to the i column: hanashi, machi, kaki, kai, kaeri
• Suru gives shi and kuru gives ki; shikata is the way, shiyasui is easy to do
• Kata is a noun, so kanji no kakikata, not kanji o kakikata
• Bare stem clause joining belongs in writing, not in conversation
• Tai for yourself, tagatte iru for a third person

If you get one thing from this guide, make it the habit of saying the stem aloud when you learn a new verb: taberu, tabe; nomu, nomi; hanasu, hanashi. Everything in this article follows from that one syllable.