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.
Ryuto begins dating Runa, despite his friends' warnings about it being "a joke for those popular types". He feels anxious about his classmates' judgment while planning his first date with her.
Ryuto is shocked as Maria, who once rejected him in junior high, transfers to his school, making it challenging for him to maintain distance, and he is further astonished when Nicole informs him about his girlfriend's upcoming birthday.
Ryuto's class announcement about being Runa's boyfriend leads to Maria's abrupt exit, and a subsequent conversation reveals a surprising connection between the two girls.
Runa invites Ryuto to the beach to celebrate their one-month anniversary, but a typhoon strands the two and forces them to spend the night together in an inn.
