三日
みっか · mikka · JLPT N5 · noun
days
📅 三日 = three + day; mi (three) + ka (day), read mikka
Uses the native Japanese counting words: mi from mittsu (three) plus ka, the old counter for days. The doubled k is just emphasis that crept in over time. Same pattern as futsuka (2nd) and yokka (4th).
三 — three horizontal strokes 一 + 一 + 一
三 is a pictographic numeral: three stacked horizontal lines representing the number three, parallel to 一 (one) and 二 (two). The form has been stable since oracle bone script. It carries no phonetic component; the meaning 'three' is direct and visual.
日 — pictograph of the sun
日 is a pictograph of the sun, originally drawn as a circle with a dot or stroke inside representing the sun's substance. Over time the round shape was squared off into the modern rectangular form. It means 'sun' and by extension 'day'.