folk · falsezh
忙
the story everyone tells
忄 (心)
heart
亡
to die, to lose
the heart, lost
The reading everyone loves: busy = 心 (heart) + 亡 (death) — when you're too busy, the heart dies.
but read it straight
A gorgeous poem, not the build. 忙 is 形聲 (phono-semantic): 忄 (heart) marks the category, and 亡 is there only for the SOUND (máng) — the character simply spells the word ‘busy’. Reading ‘the heart dies’ into 亡 is 望文生義, a later mnemonic, not the history. Real as poetry; this tool just tells you which is which.
source · 忙 = 忄 (semantic) + 亡 (phonetic, máng), a 形聲 character; a doublet of 忘 — Wiktionary / 漢典