Kanji for Fire — 火

火 is read hi on its own and ka in compounds, and it means fire in every sense — a flame, a blaze, heat itself. At four strokes it is one of the first kanji Japanese children learn, and it doubles as the radical inside dozens of heat-related characters such as 焼 (burn) and 災 (disaster).

The shape is a picture: a central flame with sparks flying off to either side. Written small at the bottom of another character it flattens into 灬, four short dashes, which is why 熱 (heat) and 無 have that row of feet underneath.

火 is also the second day of the week. 火曜日 (kayōbi) is Tuesday, named after Mars, the fire planet — the Japanese week runs through sun, moon and the five classical elements. In compounds it turns up in 火山 (kazan, volcano), 火事 (kaji, a house fire) and 花火 (hanabi, fireworks, literally “flower fire”).