Childhood friend of Takezo and Matahachi. Otsu was raised by Matahachi's family and arranged to marry Matahachi. Plans go awry when Matahachi runs off after the Battle of Sekigahara with Oko to Kyoto. Angry at Matahachi, Otsu refuses Granny Hon'iden's offer to join the Hon'iden family and seeks life and love elsewhere. Currently she is traveling with Takezo's "apprentice" Joutarou in order to find him.