Kokoro
How did Sensei's friend "K" kill himself?
Why did he kill himself?
Why did he kill himself?
The only information I have been able to find says that blood had spurted all of the doors, leaving me to infer that he shot himself.
Kokoro, Chapter 103
Coming from the book K kills himself by stabbing himself
K kills himself by cutting his carotid artery by a short knife.
Kokoro Translated by EDWIN MCCLELLAN