Reincarnation: Seoul Station's Necromancer

When former high school student Kang Woojin finds himself returned back to Earth after being forcibly summoned to a foreign planet for 20 years, he soon finds that Earth is not the same, normal place as he once remembered it to be.

After 20 years of conflict, he finds a way home to Earth, but it is now different. The Earth is afraid of monsters living in subway stations and has superheroes called the "Awakened". Woojin discovers that the monsters are a precursor to a calamity brewing beneath the ground.