Koharu tries to apply for public assistance after her husband's death, but gets refused. She discovers that her mother, who has broken off relations with Koharu, has expressed a desire to support her, and she decides to reunite with her mother for the first time in 20 years.

Koharu's neighbor calls the child guidance center after noticing that Koharu's kids spend time alone every night. Koharu decides to leave her kids with Yuki, who lives in the countryside, for a while.

Accepting the offer from Koharu's stepfather, Koharu leaves her kids at her mother's house when she needs help. Soon after, however, Koharu clashes with her displeased mother over a conversation about the past.

Koharu is touched by Riku's sensitive nature and behavior although he is a boy of few words. Meanwhile, Shiori reveals a very important secret relating to Shin's death.

After a thorough examination, Koharu is diagnosed with aplastic anemia. In the meantime, a present arrives at Koharu's house from her mother.

Without telling her mother about the illness, Koharu, aware of the deterioration of her own medical condition, asks her mother to live with her and her kids. However, the mother stubbornly refuses.

Koharu goes to Shin's birthplace and receives a letter that he left four summers ago. In the letter, he talks about memories from the past that he never told her, and the true reason why he visited Koharu's family four summers ago.

Koharu is intensely upset when she learns what Shiori has done to Shin. Koharu makes up her mind to leave the house, and her mother struggles between her two daughters.

When Koharu is hospitalized, her mother secretly undergoes an aptitude test to become Koharu's donor. Meanwhile, Koharu's stepfather learns that Koharu is ill and that Shiori is deeply involved with Shin's death.

Nozomi thinks that Koharu may be ill and tries to find out the truth. Meanwhile, Sachi receives a call from Shiori, who has been missing.

The results of the aptitude test that Shiori took to become a donor for Koharu are revealed.