Hmmm.... something's not right. Almost feels like he's possessed by something, he didn't show any hint of this kind of sadistic murderous rage during his time with the others. It was like as soon as Dragon's Heart contacted him it flipped a switch in him.
He still needs to kill his classmates, who drove him to suicide. He killed the King and Aries because they ruined his afterlife by forcefully reviving him just to be discarded again.
How would you feel when finally got away from a toxic lover and cruel relatives who abused you, and you decided to run away halfway across the world? Only for some random pissant to kidnap and force you to interact with them just to be abused again and discarded because they deemed your worth in life was less than a Quad Amputee who is mute?