Tadakuni's younger sister

Tadakuni's younger sister (Tadakuni no imōto) is a first-year student at Central High. Her mild-mannered older brother studies a year above her at North High. She is referred to by name as ‘Mei’ by Yoshitake’s older sister.

Appearance
Tadakuni's sister is of a short and slim stature. She wears her light brown hair in twin tails secured by pink bands and is usually seen in the Central High uniform, occasionally with either a blue jacket or a yellow sweater. She is depicted with prominent, sharp canines which are seen when she lashes out at the main trio or gets angry.

Like Yoshitake’s and Motoharu’s older sisters, she is never depicted with her eyes shown. In close-ups of her face, her eyes are generally covered by her hands, her hair or some other convenient method.

Personality
Tadakuni’s younger sister is quick-tempered and is ready to resort to physical violence, especially against her brother and his friends. On the other hand, she tends to get over-excited when anything good befalls her, going so far as to throw her bag far up a tree in one instance. She is also embarrassed when this side of hers is pointed out.

However, despite her strength and brutality, many characters (maybe including her own brother) are worried about her safety. She is also curious by nature and not above listening in secret to Tadakuni and his friends.

She has the habit of repeatedly pulling at a strand of her hair, especially when nervous.

Abilities
Immense Strength: Tadakuni's sister possesses a great deal of physical strength, which often leaves the main trio in shock. She incapacitates Tadakuni with a kick to the stomach, overpowers Karasawa in another instance, and overpowers Hidenori and Yoshitake with a single hand each when they both try to attack her. She is also able to shake a crane game machine that the combined might of the main trio could not budge.

Trivia

 * She has 15 appearances in the manga out of 139 total chapters (including extras).
 * She came in 9th in the character popularity poll, beating out the likes of Yassan and Ringo.