indispensable character; must-have character
Gaming slang for a character so strong or useful that they are considered a basic right to have; often used in gacha games or competitive contexts.
In this game, she is truly an indispensable character.
For beginners, it's recommended to reroll until you get a must-have character.
Compound of 人権 (human rights) and キャラ (character). The term humorously implies that having this character is as fundamental as a human right, originating from Japanese gaming communities.