This is really not mechanical ascension - Chapter 37 - This Must Be Infighting Within the Fierce Tiger Gang!

Leo awakens in a world he doesn’t recognize, with no memory of who he is or why he’s there. All he knows is that survival isn’t just a necessity—it’s his only chance to uncover the truth.Thrown into a brutal test for assassins on a hostile alien planet, Leo quickly discovers an extraordinary instinct for combat and evasion—abilities that feel second nature, yet remain a mystery even to him.But as the blood-soaked trials unfold, whispers of his lineage begin to surface. In a universe where gods are eternal and invincible, Leo carries the blood of the one being who defied that rule: the Timeless Assassin, a legend feared by mortals and deities alike.Now, hunted for what he represents and burdened by a legacy he can’t yet comprehend, Leo must forge his path through a deadly labyrinth of enemies, alliances, and cosmic conspiracies—all while piecing together the fragments of his forgotten past.For in the shadows of his fractured identity lies a truth that could shake the heavens themselves.

Childhood sweethearts.
The most popular person in school is my childhood sweetheart.

- Description from Novelupdates

Imagine a system that would let you create any skill you could imagine. Being the best at whatever you dreamt of becoming.Felix, who thought his whole life would remain average and ordinary despite hating it gets an unescapable chance to encounter the Legendary Truck-kun. Knowing it was a chance to change his life, which was a repeat of struggle every day, he happily accepted his ticket to Isekai.Waking up in the body of a wounded boy in a fantasy world, the boy finds out that his fate seems miserable. After nearly experiencing something worse than death, he finally awakens the Great Skill Creation System.Creating skill after skill that lets him achieve his goal, Felix treads upon the darkest of secrets and conquers a myriad of worlds with his trustful comrades. Watch how he changes the fates of everyone and the universe on his mystical journey.

I became a heroine who dies during the protagonist’s awakening event.