途端
とたん · totan · JLPT N3 · noun
now
⏱️ 途 road + 端 edge = right at the edge of the path: the instant it happens
Usually comes after a past-tense verb: 家を出た途端 means the moment I left the house. The sound totan can be a hook too: the instant it's done, ta-dah, something else happens.
端 — 立 stand + 耑 (phonetic, sprout)
端 combines 立 'to stand' with phonetic 耑, which originally depicted a plant sprouting with roots and shoots — its tips at both ends. The semantic 立 reinforces 'upright,' giving 端 meanings like 'end, tip, extremity' and by extension 'upright, proper.'