Youkai Gakkou no Seito Hajimemashita!

Vol.1 Chapter 12: Beniko-chan's Childhood Friend (Part 1)
Vol.1 Chapter 11: The Terrifying Dodomeki, Dr. Takahashi
Vol.1 Chapter 13: Beniko-chan's Childhood Friend (Part 2)
Vol.1 Chapter 11: The Terrifying Dodomeki, Dr. Takahashi
Vol.1 Chapter 13: Beniko-chan's Childhood Friend (Part 2)
The side-story of "Youkai Gakkou no Sensei Hajimemashita", set 1 year before the events of the main story, following Maizuka Mamekichi's first year at Hyakki Academy.Serialized on Pixiv Comic.