Risou no Himo Seikatsu

Japanese office worker Zenjirou Yamai is summoned to the Kingdom of Capua, where Queen Aura offers him an almost unbelievable arrangement: marry her, become prince consort, and live comfortably in the palace without ever needing a job again. What the kingdom needs is an heir carrying Aura's blood and Zenjirou's rare magical potential.

Zenjirou accepts, but the 'ideal sponger life' is not an endless vacation. His presence at court has political weight, and every gift, conversation, or friendship can be used by ambitious nobles. He wants nothing more than to support his wife without interfering in her rule, yet avoiding power becomes a political skill of its own if he hopes to protect the quiet marriage he came for.