Arisa is the closest thing to heroine in this novel, btw.
Because she's an older middle-age otaku woman stuck in a 11year old body, she's the closest thing to Satou's mentality in his team.
Because Satou can share more secrets with Arisa, naturally there are more conversation between them than any other girls in the team, as she is the only person he can safely discuss most matters.
They have a stronger friendship bonding than anyone else in the story.
As for Arisa's shotacon, at this point she's grown too attached to Satou for that to matter anymore.
