Tangled Hearts - The Alpha's Baby Mama - Chapter 12: He never rejected you...

I, the protagonist, was just an ordinary NEET, but suddenly I was reincarnated as a tiny white snake in a fantasy world where legendary creatures and gods exist. Not only that, but I awakened in a cave as the offspring of a terrifying Medusa Serpent.Armed with only my human knowledge and my indomitable mental strength, I'm forced to use cunning tactics and rapidly evolving skills to survive against far stronger monsters and humans... So begins the survival story of a former shut-in with incredible willpower, living as one of the lowest-ranked beasts in a world of magic!ᆖMusic suddenly started playing in my head.I'd been waiting for this moment for so long.'Snakes! Assemble'....

Eren Idril died as an old, decrepit, and piss-poor adventurer by the maws of a D-Rank monster. He had a lot of unfulfilled dreams and desires that couldn't see the light of the day after the light in his own eyes died down.

But fortunately for him and unfortunately for the world, that wasn't his end. Eren was somehow dived back in time when he was a mere teen, attending Lionheart Academy for adventurers.

When life gives him a second chance, Eren decides to exploit it to its fullest. Experience his vile deeds as he partakes in them without feeling the slightest bit of hesitation.

An advertising director is reborn in 1988 Hollywood as an eighteen-year-old blond-haired westerner named Eric Williams.

From then on, he starts writing movie scripts and television songs, becomes skilled in directing every kind of film, wins over all kinds of female celebrities, and takes the road to become a Hollywood legend.

- Description from Novelupdates

Everyone has a system they just need to meet hidden conditions to unlock it. A blacksmith system may unlock after a human walks by a forge. A master mage may unlock a system after attempting to control the mana in their body. Even something as simple as kicking a rock at a bucket can unlock the marksman system a unique system allowing for perfect accuracy. But what happens when someone reaches the age of fifteen and hasn’t unlocked their system? Walker is about to find out, time is ticking and he doesn’t want to live out his life as an ordinary human; he has dreams you know!