ʷᵒʳᵗʰ ᵗʰᵉ ʰʸᵖᵉ ᵐᵃˡᵉ ˡᵉᵃᵈˢ

Na Hwa-jin, a member of the Education Protection Bureau, begins 'true education' to protect the collapsed school authority!

want an S-Rank skill too! I want it so badly, I could die for it!
[You have awakened an S-Rank skill.] [But it only works when you die.]
This is

After being held in disdain and having his life put in danger, an orphan from the Demonic Cult, Cheon Yeo-Woon, has an unexpected visit from his descendant from the future who inserts a nano machine into Cheon Yeo-Woon's body, which drastically changes Cheon Yeo-Woon's life after its activation. The story of Cheon Yeo-Woon's journey of bypassing the Demonic Cult and rising to become the best martial artist has just begun.

After being accused of murdering a colleague, Cassian Lee came to his death. The moment he thought it was all over, his soul was suddenly possessed by a boy’s body and he awakens as a villain.

One day, amidst a boring life, an invitation message appears before my eyes. [Would you like to enter the tutorial world?]

Following it is a difficulty-selection window. [Easy] [Normal] [Hard] [Hell]. I select hell-difficulty without hesitation.

And I regret it.
I know it said hell-difficulty, but this is just too much

15 years remain till termination of service. The ending is known only to me.
'I am a veteran'