KanjiJLPT N4
Remainder

remainder, leftover, balance

Mnemonic

A lightning strike crashes into the colosseum, obliterating the crowd and most of the fighters. Only one gladiator survives the devastation—scarred, alone, kneeling in smoking ruins. He is the remainder, a cruel trace of what once was a grand spectacle.
Additional thoughts
Picture the gladiator on his knees in a blackened, empty arena—everything destroyed around him. He lingers as a damaged remnant. The cruelty of surviving when all else is gone reinforces the kanji's connotation of harm and incompleteness.
Quick recall
A lightning strike destroys the arena; one lone gladiator survives as the remainder.

Details

The keyword for 残 is remainder. This kanji conveys the idea of something being left over or staying behind after the rest has gone. It also carries connotations of cruelty or harm, as what remains can be something damaged or incomplete. The sense extends to things that linger or survive, such as remnants of the past or traces that persist after an event.
On'yomi
ざん、さん
Kun'yomi
のこ.る、のこ.す、そこな.う、のこ.り