Based off of a webtoon! Castle Swimmer!
so not exactly. Basically, the beacon is meant to fuffill prophesies, and make people happy and the world a better place. No one knows exactly what he looks like, so every kingdom has a different idea of who he is, imagining that he's some sort of celestial being with infinite wisdom and power.
The prophesy of the prince's kingdom is basically that he has to kill the beacon. Supposedly, his blood being shed will put an end to the terrible curse on his people. The prince is the only one not affected by the curse, a mer with no scars on his body