Hasebe has been very depressed recently. Why did he forge such a sword?
The Shinsengumi's five swords were also very depressed. Why did they forge that sword?
The mysterious knife is the most depressing. Why do you feel so deeply disliked when it comes? (Actually not)
Yes, the protagonist is the extra knife! I just came up with this idea and opened the trap of Bo Yinggui (meow meow meow?)