It may have been the curse of the black lilies that bloomed early in the winter--. It has been 18 years since the new and threatening virus "CLII," which killed more than 50% of minors, was completely contained. People have completely regained their normal lives, but it has left a huge mark and problem in the society.... A girl who has yet to realize its impact, Sasamori Hana, is a third-year student at Naeshiro High School in Sapporo. She is a quiet girl, but inside she always feels anxious. With only a few days left until graduation, Hana finds herself repeating the same day over and over again. "Ah... that's right. I like Itsuki-chan..." Hana strongly wishes for the happiness of "Itsuki-chan" who saved her in the past. She's not even exaggerating it, she would do anything to make it happen. But she thought the second time, "no, my feelings won't make her happy..." She thought it was something she shouldn't admit, and it would just ended as "a whim of puberty." However, that realization led to a deep, deep "curse".... This is a story of love that weaves between two people in order to persist through such "love" and "curse."