Chainsaw man

 CHAINSAW MAN

Chainsaw man takes place in a world where devils exist, and devil hunters have to kill them to keep the public safe. The story follows Denji as he learns to use his powers to kill devils.

Denji got his powers by making a contract with a devil. He gives the devil his blood so he can use its powers. He uses his contract to defeat other devils. He is only half-devil so the devil hunters use him to take down more powerful enemies. Denji finds a family in the devil hunters, because, unlike the other humans, they see him as a person and see him as a friend.

It's a very good book series and it's my favorite manga. Super cool.