To My Beloved Enemy

This is the 562nd time I've killed this guy. Hundreds of years ago, Dong-Yi was forced into immortality by the monster 'Shin-Young'. Every time, he looks for a chance to get revenge on Shin-Young, but it's nearly impossible to kill the immortal, so they live together in a strange state of near-death. However, one day, after killing Shin-Young, who always gets on his nerves, Shin-Young, who he should have returned alive with a smile, doesn't return.. Dong-Yi goes out to look for him with an anxious heart, but when he meets Shin-Young again, he strangely seems to have lost his memories of him..? "If you forget me, how am I supposed to get revenge..!"