SSS-geup Geurimjaengi Sohwansa

One day, Shin Jin-Ho and his coworkers were suddenly swept into another world by an earthquake...
It turned out this other world was identical in every detail to the webtoon drawn by his older brother. His brother, a long-time unknown writer, had become frustrated by repeated failures with his next projects, grew pessimistic about his own work, and vanished somewhere... Only Jin-Ho, who knew the worldview and story of his brother's webtoon inside out, could properly navigate this other world. Thus, Jin-Ho sets out on a journey with his coworkers, aiming to achieve two goals at once: escaping this other world to return to their original one, and discovering the whereabouts of his vanished brother.

(Source: KakaoPage, translated)