Ai no Kanashimi Chouma

Ginga is practicing. He sees Echidna, and goes to speak with her, but she's forgotten everything. He takes her home, where the others remember how she sacrificed herself for him.
Hishou tries to hypnotize her into remembering, but she becomes a baby. When she wakes, she decides she's in love with Hishou.
Chouma Vampire (a mosquito) starts out into Tokyo, sucking people dry of blood.
Kirari, on the tv, singing, makes Echidna run away in pain.
Vampire recognizes her as the betrayer, and goes after her. Ginga comes to help her, and fights Vampire, first normally, and then as Owl.
Echidna, finally remembering who she is, changes into chouma form. She jumps in the way of Vampire to save Owl, and gets critically injured. Owl kills Vampire.
Ginga holds Echidna as she dies.