Nao’s mother’s best friend decided to move into the house next door after her divorce, bringing along her son, Kyosuke-kun, who’s around Nao’s age. She couldn’t be more excited when she finds out he’s handsome—more so than his little brother, the reticent Tomoyasu. Nao’s not sure how to handle the excitement of living next to these handsome siblings, but little does she know, the excitement is just getting started…!
During the Summer festival, fireworks burst in the sky, sending sparks dancing overhead... and between Nao and Kyosuke! Now closer than ever, Nao quietly wonders if her friend might become something more until Tomoyasu speaks the words she, he, and Kyosuke are thinking: "Are you guys together now, or what?" Nao is devastated when Kyosuke immediately denies it, and Tomoyasu explodes over his brother's indifference. Finally, he declares war with Nao's heart on the line, but Kyosuke is still unmoved... or is he?