'Jeon Jeongguk was the first ever king to come out as gay and marry a guy.' Every student who majored in history knew this fact. Even Taehyung. But what he didn't know was that he was that mysterious war prisoner who Jeongguk fell in love with and married. What happens when Taehyung and Jimin fall into the Bermuda Triangle and land right inside a battlefield, five hundred years before the present time?