Simple Japanese Verb Conjugation Patterns
In terms of morphology, the Japanese language is quite unique as it exhibits both isolating and agglutinative properties. As the meaning of a sentence can vary greatly based on how verbs are inflected in Japanese, being able to conjugate each verb into its respective stems in order to add suffixes to verbs and convey specific meanings is an essential step in increasing your Japanese proficiency. In this article, I will be going over how verbs in the Japanese language are inflected and conjugated and how the Japanese kana system is cleverly connected to the inflection system itself.
What is agglutination?
In case you were wondering, agglutination is a linguistic property in which a language makes use of multiple suffixes or prefixes on one word to convey a meaning which may be accomplished by separate words in another language. In Japanese, most agglutination occurs in its verbal system. As an example in Comparison to Japanese, to express the desire for an object or to perform an action in English, we use the separate verb 'want' in correspondence with the action verb which we wish to perform. In Japanese however, expression of desire to perform an action is accomplished by conjugating the verb itself rather than using a separate verb. For example, the verb "to work" in Japanese is（働く） -（はたらく）- (hataraku), and to express the desire to work, the verb itself is conjugated into 働きたい（はたらきたい）(hatarakitai); （今日は働きたいです。）（きょうははたらきたいです）- (kyou wa hatarakitai desu) - (I want to work today). This is where agglutination starts to come in, as the 'tai' suffix (added from the polite stem) can now be further suffixed to convey different meanings such as: (働きたければ）-（はたらきたければ）- (hatarakitakereba) - (literally: "if want to work") and （働きたくない）- （はたらきたくない）- (hatarakitakunai) - (literally: "not want to work"). This morphological system is quite different from English, and it may take some time and practice to get used to.
Japanese Verb Types and Stem Types
There are three verb groups in the Japanese language, and the conjugation patterns discussed in this article primarily apply to group one verbs, which encompasses virtually all Japanese verbs except for the two exception verbs (Group 3) and the Ichidan Verbs (Group 2), which are various verbs ending with （る）that do not follow conventional group 1 conjugation rules. All of the group one verbs will end with a hiragana character, so you do not need to know the to read the kanji associated with the verb to predict the conjugation stems.
Kana Conjugation Pattern
If you look at the Hiragana chart above (reading from the right), you will see that the five basic Japanese vowels are organised from top to bottom (a, i, u, e, o). Then, each of these vowels is paired with a respective consonant to form syllables. Every Japanese verb ends with an (u) - （う) sound, categorised by the central row of the chart. There are five rows in the hiragana chart, and each one cleverly corresponds to one of the five verb stems. You can easily which stem change a group one verb will undergo based on its ending. For example, if we take the verb 行く -（いく）-(iku) - (To go), and we needed to conjugate it into its negative （ない）form or polite （ます）form, it is as simple as locating its ending （く）on the hiragana chart and then moving up or down on the column to the respective stem which we which we need. The negative stem is （か）- （行かない）so we need to move up two columns from （く）and then we find （か）. The polite stem for a verb ending in （く）is （き）, so we move up one column on the chart from く.
働く -（はたらく）- (hataraku) - (to work)
読む -（よむ）- (yomu) - (to read)
買う -（かう）- (kau) - (to buy)
話す -（はなす）- (hanasu) - (to speak)
持つ （もつ）- (motsu) - (to hold)
To get the polite stem, move up one column on the hiragana chart.
To get the negative stem, move up two columns on the hiragana chart.
To get the conditional stem, move down one column on the hiragana chart.
To get the imperative stem, move down two columns on the hiragana chart.
Verbs which end in う do not change their stem to あ in the negative stem, instead replace it with わ (wa).
The same conjugation rules will apply if you come across a verb ending with a Dakuten Hiragana symbol such as 泳ぐ - （およぐ）- (oyogu) - (To swim) or 遊ぶ - （あそぶ）- (asobu) - (To play). I will provide a table below documenting these kana in case you are unfamiliar.
Hiragana Dakuten Chart
With each verb stem, you can further conjugate and suffix verbs to convey a variety of different meanings.
The polite stem is primarily used to conjugate each verb into its respective polite form (positive, negative, and volitional), although it is also often used as a stem to pair a verb with some other specific verbs and nouns.
働き始める (hatarakihajimeru) - (To start working)
読みたい (yomitai) - (Want to read)
買います (kaimasu) - (To buy [polite])
話し方 (hanashikata) - (Way of speaking)
持ちました - (mochimashita) - (Held [polite])
The negative stem is primarily used to conjugate a verb into its respective plain negative form, although it is also used as the stem for conjugations concerning necessity as well as the causative form.
働かなければならない - (hatarakanakerebanaranai) - (Need to work)
話さなかった - (hanasanakatta) - (Did not speak)
The conditional stem is used to conjugate a verb into its respective conditional and potential forms.
買えば - (kaeba) - (If buy)
働ける - (hatarakeru) - (Can work)
The imperative stem is used to conjugate a verb into its respective plain imperative form.
行こう - (ikou) - (Go!)
Ichidan Verb Notice
There are verbs in the Japanese language such as 食べる（たべる）(taberu) - (to eat) and 信じる（しんじる）- (shinjiru) - (to believe) which are considered "Ichidan" or group two verbs and are most often conjugated by simply dropping the る ending. Despite this however, they still retain a stem change for the conditional and imperative forms.
食べれば - (If eat)
食べろ - (Eat!)
信じれば - (If believe)
信じろ - (Believe!)
There are two irregular verbs in the Japanese language:
する - (suru) - (To do)
来る - (kuru) -（くる) - (To come)
Naturally like most exception verbs in any language, you cannot always accurately predict the verb stem changes. There are many verbs in the Japanese language which are derived from nouns conjoined with the verb （する）.