Masako Aoi, from the series Senpai is an Otokonoko, is the grandmother of Saki Aoi. She is a supporting character who serves as Saki’s primary guardian and caretaker. Masako lives with Saki, and the two of them form a small household together. Her son, who is Saki’s father, is deeply absorbed in his work involving whales and is rarely present at home. Because of his absence, Masako takes on the responsibility of raising and looking after her granddaughter. She cares for Saki greatly and is a stable, protective presence in her life. Masako’s personal history includes the loss of her husband during the time Saki was in middle school, which further solidified the close bond between grandmother and granddaughter. In terms of appearance, she is depicted as an elderly woman with gray hair, often styled up, and green eyes. Her role in the story is primarily that of a family anchor, providing a nurturing home environment for Saki. Her motivations center on Saki’s well-being and happiness, stepping in where Saki’s father is absent. There is limited publicly available detail about her personality beyond her caring and guardian nature, and she does not possess any supernatural or combat-related abilities. Her development throughout the narrative is not heavily explored separately from her function as Saki’s supportive grandmother.