Kouguu no Omega: Yukihana no Shou

Ilia, the thirteenth prince and an Omega from a small country, entered a political marriage with King Khalid of the Hanu Kingdom. Despite overcoming many hardships and deepening their bond, Illia receives news that his father has fallen ill and resolves to return to his homeland...!? The long-awaited continuation of this dazzling and sensual harem Omegaverse saga!

(Source: MangaUpdates)