Yuma and Hotaru have been friends since childhood. It is only natural that when Yuma is nervous about her new boyfriend, she asks Hotaru and her boyfriend along for a double date. But when Hotaru offers herself to Yuma as “practice”, both girls realize that they’re more interested in each other than they are in their own boyfriends. With boyfriends in the foreground but a secret, passionate tryst in the background, will Yuma and Hotaru try to forget what happened between them or have they fallen into a trap of true love and betrayal?

Yuma is growing apart from her boyfriend…and into the arms of her best friend, Hotaru! But Hotaru has guy problems of her own when her boyfriend, Fujiwara, starts to suspect that Hotaru and Yuma may be more than BFFs. Will the girls be able to keep their hidden love on the down low?

Life isn’t going so hot for Yuma after her break-up with Takeda. But things only get worse when Fujiwara snaps and intimate shot of her and Hotaru… and then asks to join in! To top it all off, Yuma finds out that Hotaru has a big secret she’s been hiding! Can Yuma handle the truth when it is finally revealed? Or will she run away?

Takeda catches Hotaru and Yuma together in a compromising situation, but he's not exactly sure what it is he saw them doing. He's not the only one who is confused. Yuma feels like Hotaru is just leading her on and yet she still can't stop thinking about her friend. Will an overnight trip to the beach clear the air or make things even messier?

「好きな人とする前の練習」を口実にして、武田と別れた後も蛍とヒミツの関係を続けている由真。大学受験を前にしても、勉強が身に入らない様子の由真を不審に思った武田は、「由真は誰か悪い男に騙されているんじゃ？」と藤原に相談する。蛍と甘いひとときを過ごしていた由真だが、突然、蛍がある言葉を放ち─…!?

蛍も私のことが好き…？　かすかな期待を抱く由真の心は、蛍の「妊娠しちゃったかも」という言葉に打ち砕かれる。耐えきれずに泣く由真を抱きしめ、告白する武田。そんなふたりをみていた藤原は、蛍と由真が絡み合う写真をSNSに投下して…。男女四人、絡み合う想いの行末は…。衝撃作、ついにクライマックス!!