The protagonist and straight-A student, Nasa Yuzuki, meets Tsukasa Tsukuyomi on the streets of a snowy day before his high school entrance exams, and immediately falls in love. As he tries to cross the street to speak to her, he is hit by a truck. Tsukasa risks herself to save his life and tries to leave without a word, but Nasa, who imagines her as the Princess Kaguya, chases after her and confesses his feelings despite his severe injuries. When Tsukasa agrees to go out with him on the condition he marries her, Nasa accepts without a second thought. He loses consciousness shortly afterwards.

Upon waking up in a hospital room, Nasa devotes himself to his rehabilitation and studying, and after being discharged is accepted into high school in the top percentile one year later. He could not forget Tsukasa, however, and having lost the will to go to school he declines the offer of admission. He instead spends his days working service and delivery part-time jobs, which would enable him to meet many people, in the hopes of seeing Tsukasa again.

Years go by without any sign of Tsukasa, when she suddenly appears before him on his eighteenth birthday in order to marry him as promised. Although many mysteries still remain, the two become man and wife, deepening their love for each other with every passing day.

Note: Characters from or who closely resemble those from “Hayate the Combat Butler” by the same author will sometimes make an appearance.