15 year old Kimiko Iruka moves to a different town due to a tragedy. Her now single father, who is a high school teacher, gets a job at Morinomiya Academy. Not only that, she has a toddler sister, Hanami Iruka, that she has to help look after. Hearing that there's a daycare in the school, Kimiko and her father both agree to enroll Hanami there, opening up a new world for all of them.