After wrestling with godan verbs and their five-row gymnastics, here's the good news: ichidan verb conjugation is dramatically simpler. Most of the time, you just drop る and attach the suffix.
Kami-ichidan and Shimo-ichidan: Same Rules
Whether a verb is kami-ichidan (upper) or shimo-ichidan (lower), the conjugation rules are identical. So we cover them together.
The Core Rule
Forms 1 & 2: drop る. Forms 3 & 4: dictionary form. Form 5: る → れ. Form 6: る → ろ.
Stem and Ending
Ichidan verbs change the last two kana together, unlike godan verbs which only change the final kana.
The Six Forms
Using 起きる (kami-ichidan) and 食べる (shimo-ichidan):
| Form | Name | 起きる | 食べる | Attaches to |
|---|---|---|---|---|
| 1st | Irrealis | 起き | 食べ | + ない |
| 2nd | Continuative | 起き | 食べ | + ます |
| 3rd | Terminal | 起きる | 食べる | end of sentence |
| 4th | Attributive | 起きる | 食べる | + noun |
| 5th | Hypothetical | 起きれ | 食べれ | + ば |
| 6th | Imperative | 起きろ | 食べろ | — |
Notice the pattern:
- Forms 1 and 2: identical — just drop る
- Forms 3 and 4: dictionary form unchanged
- Form 5: る → れ (+ ば)
- Form 6: る → ろ (direct command)
Side-by-Side with Godan
| Godan (読む) | Ichidan (食べる) | |
|---|---|---|
| Negative | 読まない | 食べない (drop る) |
| Polite | 読みます | 食べます (drop る) |
| Dictionary | 読む | 食べる |
| Conditional | 読めば | 食べれば |
| Imperative | 読め | 食べろ |
Godan endings jump across five vowel rows. Ichidan basically just toggles between "with る" and "without る." Much simpler.
Practical Examples
| Verb | ない form | ます form | Imperative |
|---|---|---|---|
| 見る (see) | 見ない | 見ます | 見ろ |
| 寝る (sleep) | 寝ない | 寝ます | 寝ろ |
| 出る (go out) | 出ない | 出ます | 出ろ |
| 起きる (wake up) | 起きない | 起きます | 起きろ |
| 食べる (eat) | 食べない | 食べます | 食べろ |
Ichidan verbs never undergo sound changes (no イ音便, 促音便, or 拨音便). This is another major difference from godan verbs.
The 12 Exception Verbs
The 12 exception verbs (look like godan but are actually ichidan) conjugate entirely by ichidan rules:
| Verb | Type | ない form | ます form |
|---|---|---|---|
| 見る | Kami-ichidan | 見ない | 見ます |
| 着る | Kami-ichidan | 着ない | 着ます |
| いる | Kami-ichidan | いない | います |
| 出る | Shimo-ichidan | 出ない | 出ます |
| 寝る | Shimo-ichidan | 寝ない | 寝ます |
Even though they look like godan (one kanji + one kana), they must follow the ichidan "drop る" rule, not the godan "vowel-row switch" pattern.
Ka-gyou Irregular: 来る
来る (くる, "to come") is the only ka-gyou irregular verb in Japanese. Its conjugation is completely irregular — you have to memorize it.
| Form | Name | Shape | Suffix | Complete |
|---|---|---|---|---|
| 1st | Irrealis | こ | + ない | こない |
| 2nd | Continuative | き | + ます | きます |
| 3rd | Terminal | くる | — | くる |
| 4th | Attributive | くる | + noun | くる人 |
| 5th | Hypothetical | くれ | + ば | くれば |
| 6th | Imperative | こい | — | こい |
Note the irregularities:
- 1st form: く → こ (not か as godan would suggest)
- 2nd form: く → き (the whole くる changes, not just the last kana)
- 6th form: こい — completely unique
こい has a very strong, commanding tone — like barking "Get over here!" You won't use it in polite conversation, but it appears in exams and literature.
Volitional
The volitional of 来る ("let's come"): こよう
| Dictionary | Volitional |
|---|---|
| 来る | こよう |
Sa-gyou Irregular: する
する ("to do") is Japanese's most versatile verb and the only sa-gyou irregular.
| Form | Name | Shape | Suffix | Complete |
|---|---|---|---|---|
| 1st | Irrealis | し | + ない | しない |
| 2nd | Continuative | し | + ます | します |
| 3rd | Terminal | する | — | する |
| 4th | Attributive | する | + noun | すること |
| 5th | Hypothetical | すれ | + ば | すれば |
| 6th | Imperative | しろ | — | しろ |
Key points:
- Forms 1 and 2 are both し (similar to ichidan verbs)
- Imperative is しろ
Every "noun + する" compound verb follows these same rules:
Quick Reference: All Types Compared
Forms 1, 2, and 3 side by side for every verb type:
| Type | Example | 1st (ない) | 2nd (ます) |
|---|---|---|---|
| Godan | 読む | 読まない | 読みます |
| Kami-ichidan | 起きる | 起きない | 起きます |
| Shimo-ichidan | 食べる | 食べない | 食べます |
| Ka-gyou | 来る | こない | きます |
| Sa-gyou | する | しない | します |
In everyday use, forms 1 (negative), 2 (polite), and 3 (dictionary) are the most important. If you can produce these three, you're already conversational.
Summary
- Ichidan conjugation rule: drop る, drop る, dictionary, dictionary, る→れ, る→ろ
- No sound changes for ichidan verbs — much simpler than godan
- 来る is fully irregular: こ, き, くる, くる, くれ, こい
- する is also irregular: し, し, する, する, すれ, しろ
- The 12 exception verbs look like godan but must conjugate as ichidan
Practice Questions
Q1. Conjugate 食べる into the negative and ます forms.
Show answer
- Negative: 食べない (drop る, add ない)
- Polite: 食べます (drop る, add ます)
Q2. What is the ます form of 来る?
Show answer
きます
来る's 2nd form is き (irregular), then add ます → きます. Note: it's NOT くります.
Q3. How do you negate 勉強する?
Show answer
勉強しない
する's 1st form is し, so 勉強する → 勉強しない.