Morita-san wa Mukuchi(2011)

OVA bundled with the special edition of manga volume 3.

Morita Mayu is a high school girl. She is extremely reticent and her silence and habit of looking at people's eyes straightly sometimes cause misunderstanding. The reason behind it is not because she doesn’t like to talk nor because she has nothing to say. The reason she rarely speaks is due to the fact she thinks too much before speaking, thus losing the timing to speak altogether. Despite this, she lives a happy school life with her classmates.