Quite often “とき” is the first word that you meet to say ‘when’ in Japanese. The kanji (時) we have seen in previous examples as the time marker.
とき is used with the standard form of the verb. Note that we need the target particle to mark the time of the action.
| 担当者がいないときに、待合室で待ってください。 |
| Please wait in the waiting room when the person in charge is not here. |
| 大学を卒業して仕事を始めたときに、毎日がつらかった。 |
| When I graduated from university and started work every day was tough. |
Quite often the particle following とき is omitted.
| 図書館で勉強していたとき、祐介はいたよ。 |
| When was studying in the library Yusuke was there. |
We can also use とき to modify the noun (something we can’t do with the conditionals).
| 彼と会った時の第一印象がよかった。 |
| I had a good first impression when I met him (the first impression of the time I met him was good). |
| 年を取った親を介護する時がいつかに来るだろう。 |
| The time will come when you will look after your parents. |
Incidentally, you may recall that we have already seen one way to say ‘when’ by using the conditional ～たら.
| 仕事が終わったら有楽町に行く。 |
| When work has finished I’ll go to Yurakucho. |