You, who tried to change how you're all alone

An incident from the Great Hiatus, in which Sherlock travels to Japan on a tip from Mycroft, deduces a bunch of odd people, and is literally forced by one of them to have emotions. Oh, and discovers that they understand his-and John's-current situations to an extent he would not wish on anyone. Prior knowledge of Kagerou Days is not needed to read this fic.