Japanese Grammar

Saying 'When': 〜時 (toki)

〜時 (toki) means 'when' or 'at the time of'. The tricky part: the tense of the verb BEFORE toki tells you whether Action A is completed or not when Action B happens.

The Tense Puzzle of ~toki

~toki attaches to the Plain Form of verbs. However, whether you use the present or past form changes the meaning dramatically.

If Action A is NOT YET DONE when B happens → Use PRESENT form before toki.

If Action A IS ALREADY DONE when B happens → Use PAST form before toki.

This is independent of the overall sentence tense. You must think about the relationship between Action A and Action B.

Present vs Past Before 〜時

Present tense before 〜時 (A not yet done when B happens)

Rule

→Verb (present plain) + 時

B happens while A is still incomplete / about to happen

日本に行く時、地図を持って行く。

→Nihon ni iku toki, chizu o motte iku.

When I go to Japan, I take a map. (I haven't left yet)

寝る時、歯を磨く。

→Neru toki, ha o migaku.

When I sleep (before sleeping), I brush my teeth.

Past tense before 〜時 (A already done when B happens)

Rule

→Verb (past plain) + 時

B happens AFTER A is already completed

日本に着いた時、友達に電話した。

→Nihon ni tsuita toki, tomodachi ni denwa shita.

When I arrived in Japan, I called my friend. (Already arrived)

起きた時、もう８時だった。

→Okita toki, mou hachi-ji datta.

When I woke up, it was already 8 o'clock. (Already woken up)

With Adjectives and Nouns

I-Adjective + 時

→忙しい時、ご飯を食べない。

When I am busy, I don't eat. (忙しい - busy)

Na-Adjective + な + 時

→暇な時、映画を見る。

When I am free, I watch movies. (暇 - free)

Noun + の + 時

→子供の時、よく泳いだ。

When I was a child, I often swam.

Comparing present vs past before toki

財布を忘れた時、困った。

Saifu o wasureta toki, komatta.

When I forgot my wallet (past=already forgot), I was in trouble.

財布を忘れる時は、慌てる。

Saifu o wasureru toki wa, awateru.

Whenever I forget (present=about to forget) my wallet, I panic.

Teacher's Advice

The Classic Trap

The most common mistake: 'When I went to Japan (行った時), I bought this.' vs. 'When going to Japan (行く時), I bought this.' The first means you bought it AFTER arriving. The second means you bought it BEFORE departing (e.g., at the airport). Always ask: When Action B happens, is Action A already finished or not yet?

JLPT Exam Patterns

•Choosing the correct tense (present/past) before toki based on the scenario (N4)
•Na-adjectives need 'na' before toki: 暇『な』時 (N4)
•Nouns need 'no' before toki: 子供『の』時 (N4)

Master Timing

Drill the present vs. past form before toki with our scenario-based quizzes.

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