Otsu (おつう, Otsū) is an orphan who grew up in Miyamoto village and is childhood friends with Musashi (then Takezo) and Matahachi. After running away from the Miyamoto Village, she now works as a servant under a master swordsman and master of the Yagyu Estate, Sekishusai Yagyu. She has been working and serving him for a year now, tending to the old swordsman whenever needed, cooking his food, bringing him out for walks, and such. Otsu isn't very polite or well-mannered due to how she was raised.