Piitan

Piitan's reason for wanting to commit suicide is the creation of the ultimate humanoid, which physically resembles him perfectly, leading to Piitan feeling inferior due to the android's abilities. He is majoring in Robotic Engineering and his real name is Houdou.

[Spoiler] The first Piitan that appears is actually the android. After stabbing the fake Taburou, he runs off into the woods. Ironically, the robot resembles the real Piitan so much that it too wants to commit suicide. [/Spoiler]

[Spoiler] During the second suicide attempt, Piitan briefly dies but comes to and begins vomiting mysterious, spherical jewels made of an unknown mineral. [/Spoiler]