一寸の虫にも五分の魂（いっすんのむしにもごぶのたましい）

Japanese vocabulary

Meaning: tread on a worm and it will turn; even a tiny bug will defend itself; even the weakest and smallest beings have their own wills, so do not make light of them

See it used in real works

• Example sentences from Japanese novels & web fiction (Massif)
• Hear “一寸の虫にも五分の魂” pronounced in real videos (YouGlish)