Sasae Mochibaru

Mochibaru is a rather timid girl, often avoiding eye contact and speaking in a low voice. She is easily intimidated by the more forceful Miri Natayama, and becomes nervous even in the presence of the calmer Kouki Akune. Mochibaru is constantly seen holding her head with both arms - one at the very least. Apparently, this is because she fears her head rolling off her shoulders otherwise; when both hands are removed, she becomes highly distressed, and does not calm down until they are back in place. Despite her meek demeanor, Mochibaru cares greatly for the Shogi Club and its members, standing up to Natayama on behalf of the freshman, and refusing to think badly of Natayama herself until she had no other choice.

(Source: Medaka Box Wiki)