After the surprising ending to their Osaka trip, Tomozaki and his friends begin their third year of high school without being able to talk things over with Hinami. Hinami herself ends up in a class away from her friends, but even there, she shocks everyone. Tomozaki goes over to Hinami's house, where he meets someone he didn't expect--her younger sister--and he realizes he doesn't really know anything about her. Can Tomozaki bring the true Aoi Hinami out of hiding from behind her mask?