The Tense Rule Is Everything
とき means "when," and it attaches like a noun. The hard part is not the attaching — it is which tense goes before it.
The verb before とき is judged against the second clause, not against now.
| Sentence | Meaning |
|---|---|
| 日本へ行くとき、カメラを買った | I bought a camera before going (in my own country) |
| 日本へ行ったとき、カメラを買った | I bought a camera after arriving (in Japan) |
Dictionary form = the action has not happened yet at that moment. た form = it already has. Both sentences are in the past; only the inner verb differs.
Attaching It
| Type | Form |
|---|---|
| Verb | 行くとき / 行ったとき |
| い-adjective | 若いとき |
| な-adjective | 暇なとき |
| Noun | 子どものとき |
Always Plain Before とき
- ○ 行くとき
- × 行きますとき
Politeness sits on the final verb, as always.
とき vs 間に
Both cover "while," with a difference in span:
| Pattern | Meaning |
|---|---|
| とき | at that time — a point or a period |
| 間に | at some point during — the action finishes inside the span |
日本にいたとき京都へ行った — sometime while I lived there.
寝ている**間 に**地震があった — the earthquake happened during my sleep.