Equipped with her two girlfriends, Amaori Renako feels like she can overcome any challenge that comes her way. But when her status as a mature, reliable oneechan is put to the test, she quickly realises she has no clue how to communicate with her sister, let alone solve her problems! It's time to summon the Quintet to help find out why Amaori Haruka's been skipping school and what they can do to fix it.