One year after the events of Tsukihime, Shiki Tohno is a victim of an
accident. After this accident, Shiki awakens into a strange dream
wherein he repeats the same day over and over. There are infinitely many
endings to the day, but it always begins anew after each day.
Eventually, Shiki discovers that he must find Len, the creator of the
dream, if he wishes to escape.