Uniformed Regular Verbal Conjugation of Japanese



In this article, I introduce "Uniformed Regular Verbal Conjugation of Japanese". This rule intend to regulate most of Japanese verbs. After knowing this rule, All Japanese learners and Japanese teachers can easily understand Japanese verbal conjugation. At present, Japanese traditional grammarians classify Japanese verbs as follows.

However, under this classification, we have three separate regular conjugations. This might be certainly regular for a native speaker of Japanese but a Japanese learner is bothered by these three conjugations, whenever he / she memorizes new verbal words. He or she will be confused to choose a proper type.

Some Japanese teachers have made efforts to solve this problem. They have classified conjugations as follows after they identified Vowel I & E conjugations.

In above list. U Dropping one is identified with Five Vowels one. RU Dropping one is identified with the set of Vowel I and E one. However, there still remain two regular conjugations. Those teachers have also made good efforts to distinguish those two conjugations as follows.

An exception still appears at the end of "IRU", "ERU". So some verbs like "KIRU"(cut), "KERU"(kick) are classified into U Dropping, though they have the end of "IRU", "ERU". However, this method is quite good since I had checked the number of such a kind of verbs before. The result is remarkable so that I have found about 50 verbs applied to this exception. This number is quite a few even if it is compared with the number of English irregular verbs. So I want to call these verbs as semi regular verbs According to my classifications, All of Japanese verbs are classified as the following 2 main categories and 5 sub categories.



This rule is a kind of abbreviation. It does not have any historical and academic backgrounds. However, it is very helpful for a Japanese learner to understand Japanese regular verbs. If you would like to use this rule in your Japanese classroom, could you please introduce my web page to your students?

Basic Stem

Basic Stems
Japanesebasic stemEnglish
karu kar to cut
katu kat to win
kau kaw to buy
kesu kes to put out
sinu sin to die
tugu tug to succeed
tuku tuk to stick
tukeru tuke to attach
tukiru tuki to run out
yobu yob to call
yomu yom to read

Verbs of Uniformed Regular Conjugation have a basic stem. It is easy to find a basic stem by applying the following rules to their dictionary forms.

  • The verbs that have the end of "ERU" have the basic stem by dropping the end of "RU"
  • The other verbs have the basic stem by dropping the end of "U".
  • The verbs that have the end of a vowel + "U" have to add "W" consonants to their end of the basic stem.
  • Check the list of recessive stems type "I". 42 words are listed.
  • Check the list of recessive stems type "ER". 23 words are listed.

I pick up the examples in the following tables.


All regular verbs take the following inflections.

inflection function Japanesenote
-anai negative 打消 -azu is another negative inflection.
-eyo imperative 命令 This inflection has many variants.
-i adverbial 連用 It is followed by -masu, -tai, etc.
-rareru passive 受身
-reba conditional仮定
-reru possible 可能 It is not a standard but used commonly.
-ru adjectival 連体 It is also used as a final inflection.
-saseru causative 使役
-ta perfect 完了 It is normally used as "ta" and "te".
-you intention 意思

Combining Formulas

Combining Formulas
formula condition result
[F1] double vowels a vowel followed by a vowel
between a stem and am inflection
drop the vowel of top of an inflection
[F2] double consonants a consonant followed by a consonant
between a stem and an inflection
drop the consonant of top of an inflection
[F3] perfect inflectiona consonant followed by the perfect inflection "ita"
between a stem and an inflection
kt changed into it
gt changed into id
st changed into sit
tt,rt,wt changed into tt
nt,mt,bt changed into nd


The following tables show us the practical conjugations of each stems. The first column tagged with "raw" means the raw conjugation adding inflections, and the second column tagged with "formula" means the combining formula used to create the practical form. The third column tagged with "practical" means the practical form used in a real life.

Regular Conjugations
Vowel Ending Stem Consonant Ending Stem
tukeru (tuke-) tuku (tuk-)
function inflectionraw formulapractical raw formulapractical
negative -anai tuke + anai[F1] tukenaituk + anai tukanai
adverbial -i tuke + i [F1] tuke tuk + i tukaki
causative -saseru tuke + saseru tukesaseru tuk + saseru[F2] tukaseru
passive -rareru tuke + rareru tukerareru tuk + rarera[F2] tukareru
conditional-reba tuke + reba tukereba tuk + reba [F2] tukeba
adjectival -ru tuke + ru tukeru tuk + ru [F2] tuku
perfect -ta tuke + ta tuketa tuk + ta [F3] tuita
intention -you tuke + you tukeyou tuk + you [F2] tukou

The following table shows us the special rule applied to the perfect inflections.

Regular Conjugations of Perfect Inflection following Consonant Ending Stems
basic stemraw formulapractical note
kar kar + ta[F3] katta voicelessr,t,w changed into trt → (rt) → tt
kat kat + ta[F3] katta tt → (tt) → tt
kaw kaw + ta[F3] katta wt → (wt) → tt
kes kes + ta[F3] kesitavoiceless s chagened into si st → (st) → sit
sin sin + ta[F3] sinda voiced b,m,n changed into nnt → (nd) → nd
yob yob + ta[F3] yonda bt → (bd) → nd
yom yom + ta[F3] yonda mt → (md) → nd
tug tug + ta[F3] tuida voiced changed into i gt → (gd) → id
tuk tuk + ta[F3] tuita voiceless kt → (kt) → it

If you know the practical examples more, please go to the appendixes.

The Lists of Recessive Stems

These lists shows us recessive stems. The recessive stems have regular conjugation. There is no problem to conjugate them with this characteristics. However, their form is so confusing as not to decide which part is a real stem, because there is no logical rule to divide a consonant ending stem form a vowel ending stem.

Recessive Stems Type -I (42 words)
Japanese basic stemEnglish
-I iru i to be
iru i to shoot
iru i to coin
oiru oi to age
kuiru kui to regret
siiru sii to force
hikiiru hikii to lead
mukuiru mukui to reward
motiiru motii to use
-KI kiru ki to ware
akiru aki to get tired
ikiru iki to live
okiru oki to happen
tukiru tuki to run out
-TI otiru oti to drop
kutiru kuti to rot
mitiru miti to be full
-NI(*1)niru ni to resemble
niru ni to boil
-HI(*1)hiru hi to dry
-MI(*1)miru mi to see
simiru simi to pierce
simiru simi to freeze
kangamiru kangami to heed
-RI(*1)oriru ori to descend
kariru kari to rent
koriru kori to be disgusted
tariru tari to be enough
-GI sugiru sugi to pass
-ZI toziru tozi to feel ashamed
haziru hazi to close
-BI(*1)abiru abi to bathe
obiru obi to ware
kobiru kobi to flatter
sabiru sabi to rust
nobiru nobi to stretch
wabiru wabi to apologize
sinabiru sinabi to wilt
hurubiru hurubi to look old
horobiru horobi to be ruined
hikarabiruhikarabi to dry up
hokorobiruhokorobi to begin to open
Recessive Stems Type -ER (23 words)
Japanese basic stemEnglish
-ER kaeru kaer to return
kutugaerukutugaer to be overturned
hirugaeruhirugaer to turn over
yomigaeruyomigaer to be revived
-KERkeru ker to kick
sikeru siker to be moist
azakeru azaker to sneer
-SERseru ser to compete
aseru aser to be impatient
-TERteru ter to shine
hoteru hoter to feel hot
-NERneru ner to knead
uneru uner to wave
kuneru kuner to zigzag
tuneru tuner to pinch
hineru hiner to twist
-HERheru her to decrease
-MERsimeru simer to be wet
-GERkageru kager to darken
sigeru siger to grow thick
-BERsyaberu syaber to chat
suberu suber to slip
haberu haber to serve
  • (*1) There are no stems that have the following endings, "NIR", "HIR", "MIR", "RIR", "BIR". If you can exclude such kinds of stems, you may memorize only 20 verbs.

Irregular Inflection

The following conjugations are conformed to Uniformed Regular Conjugation except the perfect forms.

I pick up the following 3 verbs.

The following conjugations are conformed to Uniformed Regular Conjugation except the adverbial and "-masu" forms. They are mainly used for honorific expressions.

I pick up the following 5 verbs.

Irregular Conjugation

They are typically classified as irregular verbs and used the most frequently in Japanese.

Logic of Conjugation

Unfortunately, there is no rule to decide any conjugation for this kind of irregular verbs. Now I introduce a table to you so that you know this irregularity. So you do not have to understand them and the best way to learn them is only memorizing them. In the following table, I introduce 2 types of conjugation of "suru". One is modern, the other is classic. Usually we use the modern forms of "suru", but in some special cases, we have to use the classic forms

Irregular Conjugations
kuru suru
modern classic
function raw(*1) formulapractical raw(*2) formulapractical raw(*3) formulapractical
negative ko + anai [F1] konai si + anai [F1] sinai se + azu [F1] sezu
adverbial ki + i [F1] ki si + i [F1] si
passive ko + rareru korareru s + rareru[F2] sareruse + rareru serareru
conditionalku + reba kureba su + reba sureba
adjectival ku + ru kuru su + ru suru
causative ko + saseru kosaseru s + saseru[F2] saseruse + saseru sesaseru
perfect ki + ta kita si + ta sita
intention ko + you koyou si + you siyou

The Final Labyrinth

Finally we have the most serious problem about which is the dominant inflection of "si" that is the adverbial inflection, because the verb "suru" can be combined with many nouns so there are many compound verbs that have the type of irregular conjugation of "suru". We frequently use the adverbial inflection followed by "-masu" as a polite expression. So we have to find out the difference between regular verbs and irregular verbs who have the same adverbial inflection "si".

On the other hand, "kiru" has no problem, you only have to take care of the difference from the verb "kiru", which means "wear" in English.

The following list shows us the "Dominant Adverbial Inflection" provided by irregular verb "suru"

The interesting issue related to this labyrinth is that this inflection also confuses a native speaker of Japanese. The adverbial inflection "si" that appears at the end of compound verbs created by "suru" is probably regarded as another one provided by "Uniformed Regular Conjugation". For example, "ai-suru" (to love) is sometimes conjugated as a consonants ending stem just like "ai-su" whose stem is "ai-s". Also "sin-zuru" (to believe) is sometimes conjugated as a vowel ending stem just like "sin-ziru" whose stem is "sin-zi".

The first edition completed on Oct.7/2001 by (c) Mash Satou. Thank you.


Dominant Stem Type -IR

I list up the dominant stems type -IR. The total number of verbs excluding compound verbs is only 27 that is less than the number of recessive stems type -I, indeed. According to this result, you feel curious about why I have defined regressive stems as not -IR but -I. However, type -I is still recessive because its adverbial inflection is confused with one of consonant ending verbs.

Dominant Stems Type -IR (27 words)
Japanesebasic stemEnglish
-IR iru ir to get in
iru ir to fry
hairu hair to enter
mairu mair to go
meiru meir to feel depressed
-KIRkiru kir to cut
sikiru sikir to divide
-SIRsiru sir to know
hasiru hasir to run
musiru musir to pluck
nonosirunonosir to abuse
-TIRtiru tir to fall
ketiru ketir to scrimp
Japanese basic stemEnglish
-GIRkagiru kagir to ristrict
kugiru kugir to punctuate
tigiru tigir to promise
tigiru tigir to cut up
nigiru nigir to grasp
uragiru uragir to betray
saegiru saegir to interrupt
-ZIRiziru izir to touch
kaziru kazir to bite
naziru nazir to scold
neziru nezir to wrest
maziru mazir to be mixed
yoziru yozir to twist
huminiziruhuminizir to tread on

Practices of Conjugations

Practices 1
negative (-anai) adverbial (-i) adjectival (-ru)
basic stemraw formulapractical raw formulapractical raw formulapractical
kar kar + anai karanai kar + i kari kar + ru[F2] karu
kat kat + anai katanai kat + i kati kat + ru[F2] katu
kaw kaw + anai kawanai kaw + i kawi kaw + ru[F2] kawu
kes kas + anai kesanai kes + i kesi kes + ru[F2] kesu
sin sin + anai sinanai sin + i sini sin + ru[F2] sinu
tug kag + anai tuganai tug + i tugi tug + ru[F2] tugu
tuk kak + anai tukanai tuk + i tuki tuk + ru[F2] tuku
tuke tuke + anai[F1] tukenaituke + i[F1] tuketuke + ru tukeru
tuki tuki + anai[F1] tukinaitoki + i[F1] tukituki + ru tukiru
yob yob + anai yobanai yob + i yobi yob + ru[F2] yobu
yom yom + anai yomanai yom + i yomi yom + ru[F2] yomu

Practices 2
conditional (-reba) intention (-you) perfect (-ta)
basic stemraw formulapractical raw formulapractical raw formulapractical
kar kar + reba[F2] karebakar + you[F2] karoukar + ta[F3] katta
kat kat + reba[F2] katebakat + you[F2] katoukat + ta[F3] katta
kaw kaw + reba[F2] kawebakaw + you[F2] kawoukaw + ta[F3] katta
kes kes + reba[F2] kesebakes + you[F2] kesoukes + ta[F3] kesita
sin sin + reba[F2] sinebasin + you[F2] sinousin + ta[F3] sinda
tug tug + reba[F2] tugebatug + you[F2] tugoutug + ta[F3] tuida
tuk tuk + reba[F2] tukebatuk + you[F2] tukoutuk + ta[F3] tuita
tuke tuke + reba tukereba tuke + you tukeyou tuke + ta tuketa
tuki tuki + reba tukireba tuki + you tukiyou tuki + ta tukita
yom yom + reba[F2] yomebayom + you[F2] yomouyom + ta[F3] yonda
yob yob + reba[F2] yobebayob + you[F2] yobouyob + ta[F3] yonda

Practices 3
causative (-saseru) passive (-rareru)
basic stemraw formulapractical raw formulapractical
kar kar + saseru[F2] karaserukar + rareru[F2] karareru
kat kat + saseru[F2] kataserukat + rareru[F2] katareru
kaw kaw + saseru[F2] kawaserukaw + rareru[F2] kawareru
kes kes + saseru[F2] kesaserukes + rareru[F2] kesareru
sin sin + saseru[F2] sinaserusin + rareru[F2] sinareru
tug tug + saseru[F2] tugaserutug + rareru[F2] tugareru
tuk tuk + saseru[F2] tukaserutuk + rareru[F2] tukareru
tuke tuke + saseru tukesaseru tuke + rareru tukerareru
tuki tuki + saseru tukisaseru tuki + rareru tukirareru
yob yob + saseru[F2] yobaseruyob + rareru[F2] yobareru
yom yom + saseru[F2] yomaseruyom + rareru[F2] yomareru