This is a story about Suimei Yakagi, the protagonist from The Other World’s Magic is too far Behind!, during his time on Earth.  The magic he uses here is a bit different from the main story, but please enjoy it as a modern version specification.

異世界魔法は遅れてる! 外伝
Isekai Mahou wa Okureteru! Gaiden
The Other World’s Magic is too far Behind! Side Story

Raw Source:

Author: Gamei Hitsuji
Translator: Gandire Alea

Main Story
Chapter List:
1. The Black Forest
2. The Doll Master
3. The Homunculus Girl
4. After the Sorrow