Tsubaki, who divorced her husband 10 years ago, has been raising Shiro on her own. Thanks to her hard work, Shiro graduated from a vocational school and successfully secured employment. However, the commute takes a long time, so Tsubaki suggested he live alone, but Shiro refused to leave the house. Realizing that Shiro had not yet left his mother, Tsubaki invited him to a hot spring inn to get him out.