Series by 中吉虎吉

Togo Asagaki fought as a squad hero on Earth before a battle with an evil leader sent him to another world. In that new land, he becomes an adventurer so he can keep helping people. A guild job brings him to the fallen Arvoln household, where Idola tests his strength as a bodyguard. He transforms into his hero form and proves powerful enough to pass. Soon he and Idola face strange monsters tied to dangerous magic seeds.