Actually, now that I think about it, I don't think Deku's ever witnessed someone get murdered, though. Besides Sir Nighteye that is, and even then he died later in a hospital due to complications of his injury rather than in the heat of battle. Still murder though. So yeah, besides Night Eye, Deku has been completely absent whenever anyone dies. I don't think he's ever even seen a single corpse either. And I dont count that * one * guy incase anyone's gonna bring him up, he got revived later on after getting bullshit ninja heart surgery it hardly counts