so police and investigation guess it is one of the idol otaku while they suspect it was the Company or another group member trying to make it big. I did think it was odd that in showing us Ruri's life we never saw her go home. My guess is it either a group member did it to become bigger since Akira took all the credit, the Company did it to stir up drama and publicity, or Akira did it herself since the life was to much for her