MTL - After Being Betrayed, The Immortal Master Ran Away With The Demon Venerable - Chapter 91 the beginning

Kain may not have been very popular, and his life felt dull, but everything changed instantly. When he wasn't at work, he immersed himself in reading and watching anime. Then, the unexpected happened.He woke up in a new world, confronted by a blue interface hovering before him. Join the journey to see how Kain will adapt and thrive in this extraordinary reality.-No Harem- Noobie Writer.

The story is about a boy entering high school, who answers a strange call from a public phone one night. The caller challenges him to a bet: She’ll remove the birthmark which he sees as the cause of so many problems, and he’ll have fifty days to win the heart of a girl he’d considered far beyond his reach. And with this, a very strange summer begins.

She is the underworld Ghost Doctor’s only disciple, who accidentally transmigrated into the body of the main wife’s daughter in the general’s mansion. She used to be a punching bag.Now, she stepped on her dregs of an older sister, put her father’s concubine in her place, and teaches any objectionable aristocratic ladies a lesson.

Her days are rather free and unfettered. But when did that cold as ice prince from the rumors, sporting a deadpan face all day long, fix his gaze on her?
He unexpectedly fawned and pandered to her like a devoted dog?

“Go away, you rotten man! Careful or I’ll needle you like a pin cushion!”

“Wife, why are you so fierce? As a husband, I’m so scared”
….the man is all smiles as he approached, his eyes gleaming with a cunning light.

- Description from Novelupdates

The super cowardly me installed Super Coward Mode, and the terrifying extraterrestrials started to look cute.“Eating the flesh of an extraterrestrial deity? You’re not human! Ew!”“Even withstanding mental manipulation? What kind of monster are you!”“Enslaving an extraterrestrial deity? You must be out of your mind.”…And then, the reactions around me became strange.