Story of The Ancient Demon King! - Chapter 30: changes I do in about the mission given to Chrono.

The celestial celestial beings who lived for more than 100,000 years were born and reborn in a small monk in a human world.
His motto: “It’s not as good as a medicinal medicine for ten years of hard work.” “Even if you practice a copper-iron bone, it’s not enough for my soldier’s attack.”

- Description from Novelupdates

“I’ve been possessed into the controversial makjang drama ‘Gwangin’ (The Lunatic). Of all roles, I’m the omega secretary to an alpha with omega-phobia. It’s hard enough hiding my identity, but I’m also in charge of all sorts of annoying tasks: managing the protagonist’s diet, wardrobe, and house; coaxing and soothing the beta he loves. My goal is to survive until the ending where the protagonist meets the strange beta who thinks even his obsession is love, leading to a happy ending… I think I smell an omega somewhere.’ ‘That’s… impossible.’ If I speak carelessly, I die. If I mess up my work, I die. If I run away, I die. And if the fact that I’m an omega is revealed… I really die. ‘Right. It shouldn’t be possible, but that’s why I feel so f*cking awful, Secretary Kim.’ Will I be able to make it back alive…?”

[I was reincarnated as an F-class Hunter.

…it’s a problem because they don’t treat me that way.]

Summoned after an unfortunate accident in hopes they could protect the world from a coming threat, Ben and his classmates are gifted another chance at life. With fame and fortune promised to whoever is willing to fight for the sake of the world it doesn't seem like a bad deal, there's just one small problem. Ben wasn't blessed with any magic or combat skills, just crafting and enchanting. While the skills themselves aren't useless they also aren't seen as being necessary to the coming war. Now not needed and alone Ben tries to find a place in the world while meeting some of its colourful characters along the way.