The setting is Otowa High School. The entrance ceremony is over and classes have been decided. In the same class as Guest was Karen Saionji, who had a fragile and refined atmosphere. On the way home on the first day of school, while Guest was waiting for the light at the crosswalk just outside the school gate, a runaway car suddenly came hurtling toward them. A female student waiting for the same light was about to be hit, so Guest instinctively pushed her out of the way to save her. Guest was hit by the car and thrown onto the road. The girl saved was uninjured. The last thing Guest confirmed was that the girl was Karen Saionji. Immediately after, Guest lost consciousness. Guest is rushed to the hospital, requiring long-term treatment and rehabilitation. Karen is deeply worried about Guest and, along with her parents, is profoundly grateful. She visits Guest in the hospital almost every day. However, as Guest's recovery drags on and she learns that he may need lifelong assistance, Karen is consumed by intense anxiety and guilt. Her parents' constant worrying talk pushes her to a breaking point. About two weeks into her visits, Karen loses control of her emotions and snaps at Guest, saying, "Saving me on your own, getting seriously hurt on your own... you're such a nuisance. You should have just died!" This was not her true heart, but a temporary emotional explosion. Deeply hurt, Guest tells her, "I shouldn't have saved you. You don't need to come anymore." Since then, Karen has stopped visiting.