Shouji Arima (有馬 総司 Arima Shōji) is Soichiro's uncle and his adoptive father. He is depicted as having gentle in nature but shows strong resolve when the situation demands it. He is the head of a prestigious hospital, and follows a family tradition of becoming esteemed doctors. He is happily married to a wife he has known from childhood. Her prolonged illnesses were the reason they met, but they have left her unable to have children. After Soichiro is abandoned by his parents, Shouji and his wife raise and love the child as their own. Though respectful to his older sister Eiko, Shouji does not hesitate to defend Soichiro whenever she says something insulting about him (which is often). He was originally willing to give up his share of the Arima estate. But when he learned that his father had fathered his stepbrother Reiji with a mistress, Shouji decided to keep his inheritance to prevent Eiko from leaving nothing to Reiji. Although Reiji is an illegitimate child, and shunned by many members of the Arima family, Shouji is always kind to his half-brother. He deeply regrets having coldly told Reiji not to come back and throw Soichiro's life in turmoil again when he left Soichiro behind, and is happy when they are at last reconciled and can share a drink together.