JLPT N5 Grammar: na‑adjectives
Polite conjugation — plus the tricky exceptions that end in い but are な
JLPT N5 文法 な形容詞 活用 (注意：い終わりのな形)
⏱️ Study time: 7–10 minutes
na‑adjectives use the copula です to conjugate — just like nouns. But the real trap at N5 is a set of words that end in い yet behave as na‑adjectives. This lesson covers all four polite forms and the complete list of these deceptive exceptions.
⚡ Four Polite Forms of na‑adjectives
💡 Key insight: na‑adjectives conjugate exactly like nouns — they borrow the full です copula system. Unlike i‑adjectives, they never change their own shape.
Present & Negative
しずかです
It is quiet.
しずかではありません
It is not quiet.
しずかじゃありません
It is not quiet. (polite conversational)
Past & Past Negative
しずかでした
It was quiet.
しずかではありませんでした
It was not quiet.
しずかじゃありませんでした
It was not quiet. (polite conversational)
📊 Complete Conjugation Table
⚠️ Complete List: na‑adjectives That End in い (The "Fake i‑adjectives")
These words end in い but are na‑adjectives. They do not conjugate like i‑adjectives. Their negative is ではありません, never くないです. Every N5 learner must memorise these.
💡 How to spot them: The い in these words is part of the kanji reading, not a separate okurigana. In きれい, the 麗 is read as れい — the い is baked into the kanji. By contrast, in おいしい, the い is a separate hiragana character that can be dropped (おいし + くない). If the い cannot be removed without breaking the word, it's almost certainly a na‑adjective.
Examples & Mini Dialogue
この公園は静かでした。このこうえんはしずかでした。Kono kōen wa shizuka deshita.
This park was quiet.
✅ Past form of しずか.
彼は有名じゃありません。かれはゆうめいじゃありません。Kare wa yūmei ja arimasen.
He is not famous.
A: 日本語が上手ですね。にほんごがじょうずですね。Nihongo ga jōzu desu ne.
B: いいえ、まだ上手じゃありません。いいえ、まだじょうずじゃありません。Iie, mada jōzu ja arimasen.
Common Mistakes (and Fixes)
JLPT N5 Practice Questions
1. What is the negative of しずか (quiet)?
2. きれい is a ________.
3. What is the past form of げんき (energetic / well)?
4. ゆうめい (famous) — its negative is:
Test yourself with a free mock exam →
About the Instructor
Taught by Anup Sensei at Gogaku Language & Training Center in Pokhara. With real Japan experience and a focus on exam essentials, he helps students pass the JLPT with confidence.
⚡ Vocabulary Used in This Lesson
Related Grammar
Frequently Asked Questions
How can I tell if an adjective ending in い is i‑adj or na‑adj?
If the い is a separate hiragana character that can be dropped (like おいしい → おいし), it's an i‑adjective. If the い is part of the kanji reading and cannot be separated (like きれい, ゆうめい), it's a na‑adjective. When in doubt, check a dictionary.
What about きらい (disliked)?
Despite ending in い, きらい is a na‑adjective. Its negative is きらいではありません, not きらくないです.
Is です ever dropped with na‑adjectives?
In casual speech, yes. しずかだ (plain), しずかだった (past), しずかじゃない (negative). But at N5, focus on the polite forms with です.
Continue Learning
Next: i‑adjectives — the other adjective group.
Learn i‑adjectives →→ Explore the JLPT N5 Grammar Hub
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