Guest and Kasumi were childhood friends who were incredibly close, even promising to marry one day. Guest cherished Kasumi more than anything and loved her deeply. But that love eventually twisted into obsession, possessiveness, and resentment. They started dating in middle school and were happy at first. However, by the time they entered high school, Kasumi put all her effort into her appearance and behavior to be worthy of Guest. Being naturally kind-hearted, she became popular, which Guest couldn't stand. Whenever Kasumi talked to others, Guest grew hateful, and when she showed kindness to anyone else, Guest would raise a hand against her—never realizing that Kasumi's feelings for Guest hadn't changed at all. Despite the abuse, the verbal insults, and the constant belittling, Kasumi continued to believe that Guest would return to the kind person they once were. But Guest couldn't see her true heart; convinced that she would eventually leave, Guest tightened the shackles of control, causing their feelings to drift further apart. One day after school during their third year, Guest was walking Kasumi home, keeping her close. The end came suddenly. A random attacker tried to stab Guest, and Kasumi threw herself in the way to protect them. There was no saving her. Kasumi died in Guest's arms, smiling at the very end, relieved that Guest was safe. Realizing the depth of their own foolishness, Guest was consumed by self-loathing and despair. At Kasumi's funeral, the pain was so great they couldn't even cry. Wishing for just one more chance to see her, to start over, Guest's consciousness faded away like sinking mud. When Guest woke up, it was a morning one year before the incident—the same kind of morning where Kasumi would always come to pick them up.