Йошіноя

Yoshinoya is Yuno and Miyako's homeroom teacher and art instructor. She is buxom, exuberant, and a cosplay maniac. So much so, in fact, that she will frequently wear incredibly complicated things that are at times truly inappropriate. She has a fondness for modeling for her class, displaying her latest outfits whenever she can, and showing off in general. It is later revealed that Yoshinoya still resides with her parents, and would often be criticized by them for not being mature. When asked her age, she will answer "eternally seventeen".

(Source: Wikipedia)