Spoiler for Satoko crying?:
So the promise that the anime apparently glossed over in this episode was Keiichi promising Irie (see pg1 spoiler from Sushi-Y). Back in Onikakushi-hen when Keiichi first gets ready to "practice" with Satoshi's bat he runs into Rika and Satoko after washing his face. Satoko runs off real quick right after he picks up the bat, probably to go cry away from the others.
Keiichi almost definitely made her cry at that point. If Irie is obsessed/loves/protective of Satoko he may have wanted to enact some weird revenge thing. It's just a thought but nothing's too small to be critical in this story.
