Weak to S.T.R.O.N.G

He fought in hell for 80 years and after defeating the demon lord, he returned to his body on earth in a vegetative state while a wormhole appears

It's a story about simple young knight. But with his abilities he proves that he is worth being a king.

Good grades, a handsome appearance, above-average fighting skills, and a little bit of righteousness. On the eve of his graduation, Kim Hyun-sung gets pushed off a rooftop ends up in a vegetative state. Unable to die, with only his hearing and consciousness alive, he spends the next ten years in hell until he suddenly returns to the day the bullying began.
?? ??, Evil school, School of Evil

Zeke Draker, the first direct descendant of the Dragon Slayer family to fail awakening. Possessing the talent of a healer instead of a swordsman, he was cast out by his family. Struggling desperately to grow stronger, Zeke met a tragic end.
At the moment of his death, mysterious words appeared before his eyes:
[The soul of an Elder Dragon is engraved upon the will of the one who persists.]
[An irreversible, promised power is being activated.]
When he regained consciousness, he found himself back

hundred years ago, “Mostro” began invading Earth from a mysterious otherworldly space that suddenly opened. During the long battle, humans with special abilities emerged. They came to be known as “Heroes” and fought against the Mostro to protect the world

After failing the Grade Nine civil service exam four times and many twists and turns, Han Maru finally succeeded in becoming a special civil servant under the Ministry of Environment. Goodbye, gosiwon! Goodbye, convenience store lunchboxes! But the joy of passing was short-lived. It turned out to be a life-threatening national secret job?! Along with the yellow dust came the demons, creatures that kill and eat humans. The Grade 9 special civil servant job involved waging war against these demons