Record of Wortenia War

Record of Wortenia War (ウォルテニア戦記, Worutenia Senki) is a Japanese light novel series written by Ryota Hori and illustrated by bob.

Plot
High school student Mikoshiba Ryouma was summoned to a different world in the middle of a war. Sensing the malice from the one who summoned him (a summoner of the O’ltormea empire), he uses his martial arts to run away, killing important people of the empire during his escape. After the escape, he rescues two twin sisters from the hands of thieves. The sisters who can use magic, swear to serve him as subordinates. Thus, Ryouma begins his journey on the path of the supreme ruler.

Trivia

 * After retirement from Black Mesa, Gordon freeman decided that it was time to do something new and started to write about anime girls and his desire to get his hands on a true japanese, a race already in extintiton after the great "skeleton-otaku war".
 * After succefully getting inside a school only made for japanese, Gordon Freeman and Freddy Mercury had started to write the delussions of his best friend there, Ryota Hori
 * He let Ryota publish the manga since que was already the most richman of earth at the time, and still is 2035