Naruto: My Hiddden Village - Chapter 37: Yorozuya

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

Felix's life on Earth had become a series of dead-end jobs, ruined relationships, and rotating apartments smaller than most postage stamps. By all accounts, even his own, he was a coward. Too afraid to move forward, to take risks. Yet when given the chance to choose between risking his life or walking away from a deadly encounter, he didn't hesitate.Moments before his untimely demise, Felix was snatched from earth and thrust into a magical world known only as ‘The Continent’. Empowered by the ‘System,' he learns that he can strengthen himself through combat and dedication. To survive he'll have to push himself beyond his limits, or else fall to the monsters all around him.Levels, stats, and magic. Death is the start of a terrible fate, but if he lives…who knows what he will become.

Ji Huan’s parents both died in a traffic accident.
Unexpectedly, his older sister also meets the same fate.
Yet everything starts when he says “goodbye” for the last time.

Hunting monsters? Genetic comparison?
Ji Huan flees with his older sister’s posthumous child to his hometown, Bade Town.
The three Grandpa, grandson, and nephew all live interdependent days.
However, inside the swaddling clothes is not a human baby,
But a monster…

Black egg body, white ring eyes, red mouth.
A child, ah! Doesn’t he have two eyes and a mouth! Resembling an egg, he is Ji Huan’s cute nephew!

Vermilion tiled wall, white lotus pond, convalescent courtyard.
This entirely neatly handsome and elegant young man: Ah Jin.
However, he told Ji Huan about the secrets of the monsters and discreetly taught him.
Bade Town is also slowly being covered in monsters…

Or, the record of a small countryside monster’s growth.

- Description from Novelupdates

Akira, was born in the slum and wishes to get out but the only way he could was to risk his life in these ruins as a hunter.