Touzainanboku!

The spin-off manga is a prequel following the four teachers of Nanamori Middle School – Tsubasa Minamino, Hatsumi Kitamiya, Shihoko Azuma and Nana Nishigaki – in their high school days. The name of the series (literally "East, West, South and North") refers to the last names of the principal characters, which each contain a kanji for a cardinal direction.