antihero; dark hero
A protagonist who lacks conventional heroic qualities, often morally ambiguous or flawed. Wasei-eigo from English 'dark hero', but the Japanese usage aligns closely with the English concept of an antihero.
wasei-eigo (Japanese-coined English), from dark hero
He often plays antihero-type roles.
The protagonist of this manga is a dark hero who will do anything for justice.
Wasei-eigo from English 'dark hero'. The term was coined in Japanese and later re-imported into English contexts, though the concept of an antihero is universal.