The Asylum Demon is the very first boss you will encounter in the game, and serves as the tutorial boss. If you choose the Black Firebombs as your gift when starting up, it is possible to kill the Asylum Demon, using the Black Firebombs, the first time you meet it, which will net you the Demon's Great Hammer. Otherwise, you might want to wait until you get a proper weapon before fighting him. On your first encounter, there is a door on the left side you can use to escape, and after getting some equipment, you'll eventually return to the room with the Asylum Demon. The Asylum Demon has pretty basic attacks, which should be easy enough to dodge. It might be wise to wear no armor in the fight, since your main objective in the fight is to stay behind the boss. When the Asylum Demon is about to do a horizontal sweeping attack (he'll twist his shoulder slightly), either roll backwards or with the attack. When you notice him flying up into the air, roll backwards since he will smash the ground. As long as you keep these two attacks in mind, as well as constantly staying behind him, the boss will go down with no trouble.