This Japanese Monogatari Isn't Lame - Chapter 486 - 319: The Function of Kelian (4000 words)

“While playing a Tsukkur erotic game that I loved, I somehow became possessed. To make things worse, I transformed into a perverted kid—one of the villains from the NTR series.”

Earth is the human civilization’s cradle, but humans cannot possibly live within its cradle for eternity.In 2264, the first deep-space colonization spaceship of human civilization leaves the solar system and enters the boundless darkness…Zhang Yuan, son of the man behind the spaceship’s main control system, is one of the half a million volunteers to embark on the 20 light-year journey to a new planet.Follow Zhang Yuan on his journey of gaining new knowledge, exploring the unknown, and finding out what's the secret behind the intelligence enhancer his father left him.

When encountering demons, a young man with two horns on his head, red hair reaching his waist, and an extremely handsome appearance leads the demons to the front.

Youdou: Actually, I really don’t want to be a master of monsters. This profession is completely useless. My ideal is to become a magic stick…, bah, it’s to become a great onmyoji.

All the monsters: My lord, wake up, you are the leader of the monsters yourself!

- Description from novelbuddy

Haruma Kazuki is a cursed (or maybe just deeply unfortunate) high school student whose lewd, panicked, or absurd thoughts literally manifest in reality — especially when he tries not to think about them. The more he denies or avoids feelings, the more chaotic and trope-heavy the consequences.