Gosh, this manga hurt me in more ways than one. Everyone seems to be wondering why Akira turned to be a "bad" ghost, but I'd like to think that ever since Akira got to talk with Haruto, he got used to being acknowledged and seen. When Haruto lost his ability to see him, it was like the feeling of loneliness became foreign to him, and he got scared of losing contact with Haruto. He prolly harbored strong feelings of "having" Haruto again by letting him go with him in the other world. However, when Kanzaki-san gave them a chance to communicate again, he realized that he shouldn't be selfish and let Haruto live his life. Hence he gave him the motivation to sing again, at least while Haruto sings, both of them feel the connection they once had. An extra chapter of Akira's POV would be rlly great, doe, as the cherry on top of this great manga.
^