expression
even a tiny bug will defend itself; tread on a worm and it will turn
Proverb meaning that even the smallest, weakest beings have their own will and should not be underestimated or mistreated.
一寸の虫にも五分の魂というから、弱い者でも侮ってはいけない。
As the saying goes, even a tiny bug will defend itself, so you shouldn't look down on the weak.
A traditional Japanese proverb. The exact origin is uncertain, but it reflects a common folk wisdom that even small creatures have spirit and should be respected.