When Ritsu was little, he was abandoned by his mother, Reiko. Ritsu belongs in the lower social strata. 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. Ritsu finally finds his mother, but learns that she is leading a happy life with her pianist son, Satoru. He thought his mother abandoned him due to poverty. Ritsu decides to take revenge on his mother. Ritsu then meets Rinka again, who is Satoru's childhood friend.