愉快 (yukai) conjugation
pleasant, happy
愉快 (ゆかい, yukai) is a na-adjective. Na-adjectives behave like nouns. The word itself never changes — you conjugate だ/です after it, and you need な to put it in front of a noun.
Conjugation table
| Form | Plain (casual) | Polite (~です) | When you use it |
|---|---|---|---|
| Dictionary / plain | 愉快だ yukaida | 愉快です yukaidesu | The form you look up. Also the casual “is ~”. |
| Negative | 愉快じゃない yukaijanai | 愉快じゃないです yukaijanaidesu | “is not ~”. |
| Past | 愉快だった yukaidatta | 愉快でした yukaideshita | “was ~”. |
| Past negative | 愉快じゃなかった yukaijanakatta | 愉快じゃなかったです yukaijanakattadesu | “was not ~”. |
| Te-form | 愉快で yukaide | — | Links to the next clause: “~ and …”. |
| Adverb | 愉快に yukaini | — | Turns it into “~ly”, describing a verb. |
| Before a noun | 愉快な〜 yukaina〜 | — | How it attaches when it modifies a noun. |
| Conditional (~ば/なら) | 愉快なら yukainara | — | “if it is ~”. |
| Conditional (~たら) | 愉快だったら yukaidattara | — | “if / when it is ~”. The everyday conditional. |
| Become (~なる) | 愉快になる yukaininaru | 愉快になります yukaininarimasu | “becomes ~” — the change-of-state form. |
| Too much (~すぎる) | 愉快すぎる yukaisugiru | 愉快すぎます yukaisugimasu | “too ~”. |
| Looks ~ (~そう) | 愉快そう yukaisou | 愉快そうです yukaisoudesu | “looks / seems ~” from appearance. |
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Why it conjugates this way
Na-adjectives behave like nouns. The word itself never changes — you conjugate だ/です after it, and you need な to put it in front of a noun.
See the full rules in the adjective conjugation guide.