~toki (when)

The ~とき pattern expresses "when" or "at the time of," but it works fundamentally differently from how English speakers typically think about time. In English, we use "when" to mark a point or period where something happens, often treating the dependent clause almost equally with the main clause. Japanese ~とき, however, frames one action or state as the temporal context or backdrop for another—it's more like "in the context of / at the moment of / during the period when."

The key difference is that ~とき isn't just about simultaneity; it's about temporal framing and dependency. When you say something ~とき, you're saying "against the background of X happening, Y occurs." This is why Japanese naturally uses the plain form (both present and past) with ~とき, regardless of the actual chronological order. A sentence like 雨が降るとき、傘を持ちます doesn't mean "when it rains, I hold [future] an umbrella"—it means "in situations where rain falls, I carry an umbrella," capturing a habitual or general truth rather than a sequence of events.

English speakers often struggle here because we default to narrative sequencing: we think "first X happens, then Y happens." But Japanese ~とき says "whenever X is the case, Y applies" or "in the temporal frame of X, Y takes place." This is why past tense (~た) can appear before ~とき even when the main clause is present or future—you're describing a completed background state against which something else occurs or is habitually done. For example, 大学を卒業したとき、就職活動を始めました ("When I graduated from university, I started job hunting") uses past + とき because graduation is a finished point in time that frames or triggers the next action.