Mikan Yuuki

Yūki Mikan is Rito's independent and reliable 12-year-old sister. Mikan takes care of most of the household work while their parents are away working and also watches over Celine. In contrast to her brother, she is very mature and does not hesitate to tease him, going as far as lying that they aren't blood-related, but quickly retracting the statement and telling the truth. Mikan also seems to have a certain lack of respect for Rito because of this (hardly ever addresses him by honorific as an older brother), but does answer him "Onii-Chan" as thanks for trying so hard to take care of her when she develops a fever and when he gives her a Christmas present.