When Ritsu was little, he was abandoned by his mother Reiko. He happens to help Rinka. One day, Ritsu gets involved in a case and gets severely injured in the head. He can die at anytime. He attempts to find his mother and be good to her before his death, and finally finds his mother, but learns that she is leading a happy life with her son Satoru. Ritsu decides to take revenge on his mother, then meets Rinka again, who is Satoru’s childhood friend.