Shachiku no Ore ga Ero de Isekai Sukuu tte!? ※Tadashi Ossan shika Inai

Aoki Soman, a good-natured engineer, gets into an accident during a quarrel with his colleague Tategawa. When he wakes up, he finds himself in an unknown country called Mt. Baiyang. There, a middle-aged man who calls himself Yi-Yan, tells Aoki that he possesses the rare power of "Yang" (lewd power). Aoki, who suddenly became the savior of Mt. Baiyang, set out on a journey with Yan to visit the sage in order to teach him the mysteries of the sun to protect this country from the demon king, Kuze no Tsuki.

(Source: Takeshobo, translated)