Guardian: The Lonely and Great God (2016)

Kim Shin was once an unbeatable general in Goryeo's military who died a tragic death. He now possesses immortality but is tired of living while everyone else around him dies. For 900 years, Shin has searched for his bride, a mortal who can pull out the sword and end his life. One day, he encounters Ji Eun-tak, a positive, upbeat high school student who can see the dead and has gone through tragic events, yet still stays strong. She claims to be the Goblin's bride who can end his immortal life, but what appears to be an easy task, only gets complicated, as the two fall in love.