Seito Shokun!(1977)

Seito Shokun!

Nakki is a girl full of energy and a torment to her new teachers. She lived with her grandparents and come back to her home, to her weak and sick twin sister and a new school. We are invited to follow her daily life with her friends in the happy and painful process of becoming an adult. They discover that friendship is the most valuable treasure they can have in their lives. From student to teacher, from a girl to woman, we go with Nakki.

(Source: Anime News Network)