Is It Wrong to Try to Pick Up Girls in a Dungeon?, Vol. 8 (light novel) — Fujino Omori

The Rakian Kingdom is on the march, a thirty-thousand-strong army headed by Ares, God of War. The target of their sudden invasion is none other than the world's greatest metropolis, Labyrinth City Orario. As the armed menace approaches in thunderous lockstep, the city's inhabitants can do nothing but...continue about their completely peaceful lives??? A prum proposes marriage, one sweet boy becomes a bodyguard, the city girl's secret comes to light, while mortals and gods alike are swept up in romance--these are the ordinary days of timeless deities and their dazzling children in the fateful city of Orario!