Inosuke is usually seen wearing a grey boar mask, with a shirtless version of the Demon hunter uniform. Without the mask he has messy shoulder length black hair and large green eyes with long eyelashes. He is described as having a girly looking face which greatly contrasts with his muscular body.
Inosuke is extremely short-tempered and proud, and makes a big deal out of fighting opponents stronger than him claiming that's his only hobby. He is a sore loser and is always trying to compete with Tanjiro and provoke him into fighting him, and usually failing. Due to growing up in the mountains by himself Inosuke has trouble interacting with others and only cares about himself most of the time.
(Source: Kimetsu no Yaiba Wiki)