とき details
write + when
kaku toki
when; at the time of
meaning: when writing
子どものとき、ここは全部田んぼだったんだよ。
kodomo no toki, koko wa zenbu tanbo datta n da yo.
When I was a kid, this whole area was rice fields. casual
大阪へ行くとき、駅でお弁当を買った。
oosaka e iku toki, eki de obentou o katta.
I bought a boxed lunch at the station when going to Osaka (on the way there). neutral
Examples
when / during — locates the main event at a time or situation
子どものとき、ここは全部田んぼだったんだよ。
kodomo no toki, koko wa zenbu tanbo datta n da yo.
When I was a kid, this whole area was rice fields. casual
学生のとき、京都に住んでいました。
gakusei no toki, kyouto ni sunde imashita.
When I was a student, I lived in Kyoto. neutral
お出かけのときは、戸締まりをご確認ください。
odekake no toki wa, tojimari o go kakunin kudasai.
When you go out, please make sure the doors are locked. formal
relative tense inside the clause — dictionary form means "not yet done then", た-form means "already done then", whatever the sentence tense
大阪へ行くとき、駅でお弁当を買った。
oosaka e ikutoki, eki de obentou o katta.
I bought a boxed lunch at the station when going to Osaka (on the way there). neutral
大阪へ行ったときさ、たこ焼き食べたよ。
oosaka e itta toki sa, takoyaki tabeta yo.
When I went to Osaka (once there), I had takoyaki. casual
Formation
{V}ときattaches to dictionary form{V-ta}ときattaches to た-form{N}のときattaches to noun
Notes
Related patterns
Similar
とき points at an occasion and accepts punctual and durative clauses alike; あいだに insists on a durative interval (ている, or a span noun) and places the main event strictly inside it — 着いたとき is fine, ×着いたあいだに is not.
Both open a temporal clause, but まえに asserts strict order — the main event precedes the clause event, always — while とき only locates the two together and delegates the order question to the tense inside the clause.