For this troper, perhaps the saddest moment was in episode 23, when Crim runs into Tsukasa, who is currently in the middle of a mental breakdown. Tsukasa just repeatedly apologizes and begs for Crim not to hit him, and a horrified Crim can only ask why a child is so convinced that everyone around him is trying to hurt him.
Crim: I'm not going to hit you! Who did this to you!?