Nakanaka Kishou na Mitsuya-san

Mitsuya-san is one of the few long-lived demi-humans in Japan. She is not very familiar with modern life, so in order to learn, she enrolls in high school at the (approximate) age of 200! With her exotic beauty and warm personality, she grabs everyone's hearts in this high school comedy!

(Source: Dengeki Daioh, translated)