Disciple of the Three Kings

Synopsis

When portals erupt across Earth, monsters pour through and push humanity toward collapse. The crisis also connects Earth to three powerful realms: a martial society, a land of magic and knights, and a demon domain. Their superhuman champions defeat the invaders, but exploit the newly awakened human Players. After trying to negotiate peace and being betrayed, Lee Ro-Woon loses everything and enters a sealed world, where he becomes the disciple of three mysterious rulers.