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.
国へ帰る時、お土産を買います。
Kuni e kaeru toki, omiyage o kaimasu.
When I return to my country, I buy souvenirs. (Before departure — still in Japan)
国へ帰った時、家族に会います。
Kuni e kaetta toki, kazoku ni aimasu.
When I have returned to my country, I meet my family. (After arrival — already home)
暇な時、何をしますか。
Hima na toki, nani o shimasu ka.
What do you do when you are free? (Na-adjective + na + toki)
子供の時、犬を飼っていました。
Kodomo no toki, inu o katte imashita.
When I was a child, we had a dog. (Noun + no + toki)

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?

A Test You Can Apply in 2 Seconds

Replace 時 with 'before/while' vs 'after' in your head. If the meaning is 'before/while doing A' → present form (帰る時 = before/while returning). If it is 'after having done A' → past form (帰った時 = after returning). This mental swap resolves 90% of toki questions without deep grammatical analysis — my students' accuracy jumps immediately once they adopt it.

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)
  • •Reading comprehension: tracking whether the toki clause happened before or after the main clause (N4)
  • •Distinguishing 〜時 from 〜たら/〜と conditionals in sentence-completion questions (N4)

Related Grammar

Conditionals: 〜たら (~tara)
Grammar guide →
Saying 'Because': から and ので
Grammar guide →
The Plain Form (Dictionary Form)
Grammar guide →
See the full JLPT N5 grammar roadmap →

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