[FallenAngelV]

Originally Posted by MuMyung

Spoiler:

They were lying when they said he was at the Watanagashi festival, it was his "alibi" in order to protect him, since they knew he was going to follow in Satoshi's footsteps and kill Satoko's uncle. Rena and Mion went to dig up the body when K1 went back to check if Satoshii's bat was there. They were hinting this to K1, saying "Bring the receipt, it's important."

Ah, I see. I'll have to go back and watch that arc again to fully appreciate this answer. Thanks.