Chiaki Minami is the youngest sister with Haruka being the oldest sister and Kana being the middle sister. Chiaki is in elementary school, class 5-2, and always gets good grades. Due to her high intellect she tends to overanalyze the simple things. Also because of her intellect she is fairly egotistic and is the meanest of the three sisters, often using the termbakayarō, which is a more harsh form for idiot, in Japanese; she says this mostly to her older sister Kana. Despite her crule demenor around others she is very polite and amiable when she is with her older sister Haruka. She idolizes Haruka and wants to be just like her.
She often is cold to Kana due to her stupid actions and selfish acts, often calling her Idiot and comically throwing her teddy bear at Kana's face. She is also somtimes seen smacking Kana with her bare hand when her bear is not near her, and her stupidity annoys her too much.
Though all this, Chiaki does love both her sisters, Though she doesnt show it much with Kana it can be seen in certain parts of the anime, Some of these include looking after Kana when she is ill, Working with her on showing Haruka they can be independant and the main example is when Chiaki has a nightmare than Kana went to the shops and never returned home, causing her to latch onto Kana for the whole day, never leaving her side, afraid that she will never come back.