Kishi to Mikado: Saiai

Kagomiya Mikado, the noble son of the Kagomiya Group, is suddenly transported to another world, where he meets and falls in love with Abel, the leader of the Kingdom Knights. However, after an attack by the sorcerer Vernon, Mikado loses the power to return to his original world. Determined to find a way back, he sets out on a journey with Abel, discovering that the key lies with the elusive elves. Despite their struggles and setbacks, they hope to overcome the harsh journey by strengthening their love and bond. But as time goes on, Abel starts to change…

(Source: Bunkasha, translated)

Note: Includes one extra chapter.