Kimika had two sons, but they divorced 12 years ago, and Kimika took in her older brother, while her husband took in her younger brother, Yuki. Eventually, the older brother became independent and left Kimika, and Yuki came to live with them instead, saying it was convenient for him to commute to university. Unlike his brother, Yuki is very Kokoro and doesn't depend on his mother, so Kimika felt sorry for him and took him on a trip to a hot spring to make him feel her love.