I think if the idol survived, she probably frames the main character either way, too bad her plan seem to backfire getting herself killed in the process by some male culprit with good physique due to able to wield and slash around a gold katana (MC and Fat Guy probably out of the suspect list)
Leon Killed her due to the dying message behind the corpse.... who knows if she's actually left handed or right handed that they might just frame the guy
and the crystal ball guy, doubt its him why would he fucking break and leave his crystalball out in the open
Definitely lack motive and needs more evidence to be presented like character relationships, they might know each other like MC and Idol
Hope they change the blood to red tho in the BD, then I might rewatch this again :/