Rito's independent and reliable 11-year-old sister, Mikan takes care of the housework while their parents are away on business. In contrast to her brother, she is very mature and does not hesitate to tease him, going as far as stating they aren't blood related, just for a laugh. Mikan also seems to have a certain lack of respect for Rito because of this (she hardly ever addresses him by his honorific as an older brother), but does answer him "Onii-chan" as thanks for trying so hard to take care