Mikashina Akeru and Michika are step sisters to the older Hanabusa Yu, but they are so close that they might as well be related by blood. Yu is a teacher at the school that both Akeru and Michika attend but is not very mature compared to her younger sisters. She is a procrastinator, lazy and childish while Akeru and Michika are very independent and capable high school girls. These polar opposite personalities live under the same roof but they somehow manage to have a fun family.