電光 でんこう石火 せっか
denkōsekka

Noun
no-Adjective

1. flash; instant; lightning (speed)

Yojijukugo
かれはそれを電光 でんこう石火 せっか はやさで仕上 しあげた。
karewa soreo denkōsekkano hayasade shiageta.
He finished it as quick as lightning.