Saeko is  Shotaro's oldest sister.  She was the first of the three Satanoka daughters to be married off once she reached age 20. she is a patient, understanding and caring woman. She believes that people should marry for true love than being forced to do so. She is very afraid of inflicting her father's wrath which is why she has never once spoken up against the plans he's made for her.  However, she is very overprotective of her younger brother to the point of speaking when not being told to speak.  

She is a doting mother to her daughter Wakana and believes that if she is a better mother to her daughter then she can protect Wakana from the plans her father has made for her as well.