Guts is the protagonist of the story. He is a tall, muscular man with a huge sword called the Dragon Slayer, a prosthetic left forearm that has a magnetic grip which also conceals a cannon. Guts is a tragic hero; he is born as one who may be able to struggle against Causality, but seemingly unable to affect it on a large scale.

The father of Baki and Jack Hanma. He is the strongest creature in the world, and is known to have mastered all styles of unarmed combat. His repertoire apparently includes all of the well-known fighting styles (such as karate, boxing, taekwondo, judo, jujutsu, wrestling, street-fighting, and so on) as well as some more esoteric ones (such as the udonde or uzunde style, an actual system used in the Motobu style of karate). He has been fighting on the battlefields, using only his bare hands, since the age of sixteen, when he fought against both American and Vietcong in the Vietnam War. Since then, it appears that he has obtained respect from the American forces, and has begun fighting as a kind of mercenary for them. It is said that when he stopped fighting for survival but for pleasure the image of the demon's face appeared on his back.

Guts