Uesugi Sachi

Koharu's biological mother. Due to an abusive husband, she left Koharu and, after marrying Kentaro, gave birth to Shiori. Working at a hotel to support the family with Kentaro's meager income, she reconnects with Koharu after 20 years when a welfare inquiry, secretly accepted by Kentaro, brings them together. It is during this reunion that she learns about Shin's death for the first time.

Their relationship remains strained, but beneath the surface, she harbors self-blame and concerns for her daughter. Despite occasional gestures like gifting an air conditioner and caring for the collapsed Koharu, she grapples with inner turmoil. After learning the truth about the accident surrounding Shin's death from Shiori, she tries to protect Shiori by silencing her and once again rejects Koharu.

Upon discovering Koharu's illness, she empathizes with Koharu's efforts to hide it from the children and undergoes HLA typing to become her donor. However, the compatibility is low, resulting in donor mismatch. Later, when Shiori hints at suicide over the phone, she shares her own burden of guilt towards Koharu and encourages Shiori to face the future with a resolve to live despite their shared guilt.

(Source: Japanese = Wikipedia || Translation = MyDramaList)