New World More Fun (Tensura x GATE)

The Sadean Empire believed the gods had granted them a new world of glass and steel to enslave when the Gate stabilized in Ginza. They were catastrophically wrong. The dimensional rift fractured upon entry, bridging modern-day Tokyo not just to a medieval fantasy realm, but directly to the border of the hyper-advanced Jura Tempest Federation.

For JSDF Lieutenant Youji Itami and Sergeant Shino Kuribayashi, the battlefield becomes completely surreal when the leader of the monster forces steps into the crossfire. Shimmering with the terrifyingaura of a True Demon Lord, the silver-haired king drops his terrifying presence to complain about his ruined weekend in perfect Japanese.

Well your not interested in the description then just read the story.