Mystery: Gray Walker

After the new Genesis War, the transmigrator Grimm awakens from a gray dream, finding himself in a collector's edition family: a dead father, a vanished mother, a school-aged sister, and a sensible young man. A phone call and a white cat open the door to a bizarre world for him. An assassin's potion is placed before him, but he remains unmoved, not because he's not strong enough, but because it's reserved for his brothers. When an apprentice's potion is placed before him, who can resist the temptation to run away? "Cheers! To the sisters! No, to the brothers, to our new car!" "Listen, you're surrounded." Machine guns, cults, secret potions, sequences, alchemy, mysticism, astrology, magic.