Ryota Hori 
Record of Wortenia War (Manga) Volume 3 [EPUB ebook] 

High-schooler Ryoma Mikoshiba finds himself summoned to another world by the warmongering O’ltormea Empire. But Ryoma is no ordinary school boy – he has both talent and training in martial arts. Escaping the O’ltormea Empire, Ryoma finds himself caught up in a conspiracy. With him and his newfound companions backed against the wall, Ryoma must cooperate with the princess of the princess of Rhoadseria to resolve an upcoming civil war. Proving his strength, Ryoma begins to advance down the road to domination.