| Chako Hamamatsu|
|Hometown:||Izu, Shizuoka Prefecture|
|Weight:||42kg (92 lbs)|
|First Appearance (Manga):||Radiowave Yunyun (Kitakou Pure)|
|Last Appearance (Manga):|
Chako is a petite young girl with short dark hair. Her most unusual feature is her large hair antennae extending from the top of her head. She wears the standard Seiryou girls' uniform, consisting of a green vest and tan (or light green) skirt, a white uniform shirt, and a red bow tied around the neck.
She is a shy and pitiful type of girl who tends to be somewhat of a crybaby. She is intensely fearful around strangers, to the point that she is dubbed the "Queen" of being shy to them. As strange "yun yun" sounds are often heard when she is around, Chako's nickname is "Yunyun".
Main article: Fujiyuki Hamamatsu
Chako's older brother, who is incredibly unlucky. As he often winds up dying and coming back to life somehow, or winding up in other unfortunate situations, she has a difficult time being around him. Yet even so, she attempts to cling to him for support.
Main article: Noto Kanazawa
Chako has a crush on Noto, but it is one-sided as he barely notices her and because she is too nervous to get up the courage to speak to him.
Main article: Iyuta Nibutani
Iyuta has feelings for her, though she does not reciprocate them due to the crush she has on Noto. As Iyuta's crush is not common knowledge, most people assume that Fujiyuki is the "Hamamatsu" that he finds attractive.
- Both Chako and her brother's surname derives from the city of the same name in the west of Shizuoka Prefecture.