Baka to Test to Shoukanjuu‎ - Volume 10.5, Me and Brother and the Mysterious Bolster

On an ordinary day, Lucius stumbled upon a strange, run-down shop. At first, he assumed it was abandoned—until he stepped inside.[You have entered the Universal Alchemy Store.][Congratulations! You are now the store’s owner.][Please craft your first potion.]Lucius blinked. 'What kind of joke is this?' But as if guided by an unseen force, he followed the instructions. Minutes later, his first creation was complete.[Love Potion: The drinker will fall in love with the first person they lay eyes on.]Lucius swallowed hard. 'Wait… does this actually work?'Before he could process it, the shop’s door swung open.Standing in the entrance was no ordinary customer—she was an elf. Long, pointed ears, mesmerizing green eyes, and a body sculpted by the gods. A visitor from another world.A dangerous thought crept into his mind.'Should I test it on her?'

Traveling to the wizarding world, Eli found that he was an Eternal.

Life is infinite, life is immortal.

“What? The talent is very poor, then I will meditate for ten years, centuries, and thousands of years, and I can always meet the promotion requirements.”

“This skill is hard? Oh, let me study it for decades to see if it’s really that hard?”

“Consuming life force, improving mental force, and this kind of good thing.”

“The enemy is here? Oh, let me find a place to hide for a thousand years, until his lifespan is exhausted and his mental power dissipates, and then I will come out again, free and endless void.”

…

This is the story of an immortal who lives in the wizarding world and then kills the endless world.

- Description from novelbuddy

The Prea gods, who saved humanity from living as slaves to other races and established the human empire, passed down their bloodline. Those who inherited their blood were born with magical talent and could become wizards. After thousands of years, the empire fell, and the world became ruled by great masters across different regions.He was a young man who grew up with his mother, never knowing who his father was. Though he possessed tremendous magical abilities, he lived as a shepherd in a rural village. Now he ventures out into the world to discover the secrets of his bloodline.