Option D. As a wingman for Riko once she discovers her feelings.Still unsure if Ruuka's there as a diversion, as comedic relief, as a foil for Riko once her secret's out, or a potential "alternate ending" where Riko can be close with Aika but not in a way that raises questions.
Plot twist, she is an uncover FBI agent and arrests Riko.Option D. As a wingman for Riko once she discovers her feelings.
Nah. It's already too late for her - she just doesn't know it yet. She's desperately trying to deny it, but she has already completely fallen. That makes the FBI bit feel like foreshadowing...Oh, she's falling, slowly but surely. ^^