The izenkei conjugation (已然形) is also called the hypothetical form and has only one function in modern Japanese: combined with + ば (ba) it is one of several conditional forms, translated as "if" or "when". No contractions occur with the izenkei. Find more information on the use of the izenkei + ば (ba) construction below.
All verbs have a regular izenkei conjugation.
The izenkei + ば (ba) can also be used to describe an observation or conclusion. In this case it can be translated as "Now that I…" [often encountered as ren'youkei + てみれば (te mireba)], as "when" or "while", describing a coincidence or one-off occurrence (used as とき toki), or as "and then" when actions are performed by the same grammatical subject.
The izenkei + ば is never found at the end of a sentence. It always ends the conditional clause, followed by the main clause.
高かければ買えない。
Takakereba kaenai.
If it's expensive, I can't buy it.
説明を読んでみればすぐ分かります。
Setsumei wo yonde mireba sugu wakarimasu.
When you've read the instructions, you will understand.
どうすればいいでしょうか?
Dou sureba ii deshou ka.
What would be the best way to do this? (Literally: If I do it now, will it be ok?)
だ (da)
The verb だ (da) doesn't have an izenkei conjugation; it is therefore not possible to contract である (de aru) into だ (da).
Present tense Conditional form
ある aru あれば areba
である de aru であれば de areba
だ da であれば de areba
です desu であれば de areba
Izenkei + ばならない (ba naranai) / + ばいけない (ba ikenai)
Special combinations are the izenkei + ばならない (ba naranai) or the izenkei + ばいけない (ba ikenai). These combinations form a prohibitive, and are translated as "mustn't". When using the double negatives mizenkei + なければならない (nakereba naranai) or mizenkei + なければ行けない (nakereba ikenai) these combinations form an imperative, and are translated as "must" or "have to".
そのような本を読めば行けない。
Sono you na hon wo yomeba ikenai.
You mustn't read a book like that.
すぐ行かなければならない。
Sugu ikanakereba naranai.
I must leave soon.
Izenkei conjugations
| Group 2 conjugations | to eat | to se |
| Rentaikei | 食べる taberu | 見る miru |
| Izenkei | 食べれ tabere | 見れ mire |
| Group 4 conjugations | to write | to buy | to wait | to lend |
| Rentaikei | 書く kaku | 買う kau | 待つ matsu | 貸す kasu |
| Izenkei | 書け kake | 買え kae | 待て mate | 貸せ kase |
| Irregular verbs | to do | to come |
| Rentaikei | する suru | 来る kuru |
| Izenkei | すれ sure | 来れ kure |
| Verbal adjectives | to be large | to be new |
| Rentaikei | 大きい ōkii | 新しい atarashii |
| Izenkei | 大きけれōkikere | 新しけれ atarashikere |
| Verbal adjective | to be good (irregular) |
| Rentaike | いい/良い (ii / yoi) |
| Izenkei | よけれ/良けれ (yokere) |
All verbs have a regular izenkei conjugation.
Izenkei + ba (ば)
The izenkei conjugation has only one function in modern Japanese. Combined with + ば (ba) it is one of several conditional forms, translated as "if" or "when". The izenkei + ば (ba) is used when there is a logical cause and effect relation.The izenkei + ば (ba) can also be used to describe an observation or conclusion. In this case it can be translated as "Now that I…" [often encountered as ren'youkei + てみれば (te mireba)], as "when" or "while", describing a coincidence or one-off occurrence (used as とき toki), or as "and then" when actions are performed by the same grammatical subject.
The izenkei + ば is never found at the end of a sentence. It always ends the conditional clause, followed by the main clause.
高かければ買えない。
Takakereba kaenai.
If it's expensive, I can't buy it.
説明を読んでみればすぐ分かります。
Setsumei wo yonde mireba sugu wakarimasu.
When you've read the instructions, you will understand.
どうすればいいでしょうか?
Dou sureba ii deshou ka.
What would be the best way to do this? (Literally: If I do it now, will it be ok?)
だ (da)
The verb だ (da) doesn't have an izenkei conjugation; it is therefore not possible to contract である (de aru) into だ (da).
Present tense Conditional form
ある aru あれば areba
である de aru であれば de areba
だ da であれば de areba
です desu であれば de areba
Izenkei + ばならない (ba naranai) / + ばいけない (ba ikenai)
Special combinations are the izenkei + ばならない (ba naranai) or the izenkei + ばいけない (ba ikenai). These combinations form a prohibitive, and are translated as "mustn't". When using the double negatives mizenkei + なければならない (nakereba naranai) or mizenkei + なければ行けない (nakereba ikenai) these combinations form an imperative, and are translated as "must" or "have to".
そのような本を読めば行けない。
Sono you na hon wo yomeba ikenai.
You mustn't read a book like that.
すぐ行かなければならない。
Sugu ikanakereba naranai.
I must leave soon.
