Happy Massacre Ending

Story:

High school student Kusakabe Makoto must work throughout the day to raise money for his younger sister's medical treatment. His father is unemployed, and his mother abandoned the children, leaving him to face bullying at work and other difficulties. Despite all this, he does not lose hope and continues to live for her sister. However, when she tells him that she does not have long left to live, Makoto falls into despair. He fears what will become of her after she dies and begins to question whether life has any real meaning beyond mere existence.