When quiet nerd Ryuto Kashima's friends force him to confess his feelings for popular girl Runa Shirakawa, his entire world is turned upside down when she actually agrees to date him.

When Ryuto boldly announces in class that he is Runa's current boyfriend, Maria bolts from the room. Ryuto follows and asks her if she is responsible for the nasty rumors about Runa. Maria's answer reveals a shocking connection between the two girls.

Ryuto adjusts to living in Runa's great-grandmother's house as the couple prepares for the upcoming summer festival. As the two work in the same shop during the day and sleep under the same roof at night, they start to imagine a possible future together.

Things have been tense between Ryuto and Runa since the culture festival. Ryuto plans to tell Maria they can't be friends anymore, but a shocking incident leads to a discovery that changes everything for Maria, Runa, and Ryuto.