Nanaka 6/17

Nanaka 6/17 (ななか6/17 Nanaka Jūnana-bun no Roku) is a 12-tankōbon manga series created by Ken Yagami and published by Akita Shoten between 2000 and 2003. The manga series was adapted into 12-episode anime series that aired on TV Tokyo in 2003. In 2004 the anime series was licensed for distribution in North America by ADV Films and released on DVD in 2006.

Plot
The story focuses on a cold and distant 17-year-old girl, Nanaka Kirisato, who only cares about studying and getting accepted into a good college. Nenji, her childhood friend, doesn't really care about school and often gets into fights. At the start of the story, Nanaka berates Nenji for fighting and tells him he needs to grow up. After Nenji tells her he never wants to see her face again, Nanaka is devastated but then falls down a flight of stairs. She loses her memories and regresses to the time when she was six years old. She also thinks that Nenji made a wish to become an adult just like her. Nenji ends up having to watch over her as she goes through high school, which causes trouble and comedic situations.