Shizune Arima is Soichiro's Aunt and adoptive Mother. She and her husband Shouji were childhood friends, and Shouji's father was her doctor. She was quite sickly as a child, and her artist father often painted her outdoor scenes as she was too weak to leave her room. As they grew up she fell in love with Shouji and the two were happily married, but she was unable to bear children. Fortunately, they adopted the young Soichiro not long after his biological mother, Ryoko, abandoned him. She never got along with her brother-in-law, Reiji. She is aware that the reason Reiji doesn't like her is because of his jealousy towards her marriage to his older brother, Shouji. She eventually saves Soichiro from Ryoko's wrath, slapping her for her treatment of him as a child. She has an unnamed mother and older brother who are never seen within the story.