Yuusha no Segare - Volume 1, Chapter 2 − My Mother is Strong Part 1

After choking to death on a watermelon, Rong Jiahui thought that she would enter the netherworld and be reincarnated.

But when she opened her eyes, she discovered, to her very horror, that she had returned twelve years into the past…

Looking at the beautiful and awkward “little brother” that would be conferred the title of Marshal in the future for outstanding military service, she almost let out a snort of laughter.

She firmly decided to hug the thigh of this little brother, and climb to the top of her life!

The plan was beautiful, but it had just one problem.

Why had this little brother… suddenly turned into…

A little sister…

- Description from Novelupdates

Until he became the lowest-ranked master, his lonely and luckless life never changed.

Suddenly one day, a descendant injected him with a nanomachine, and the machine started ‘speaking’ to him.

“What? What are you talking about?”

This was beyond the boy’s knowledge, he turned pale.

The Nanomachine linked to his cerebrum realized the User was not understanding a single word it said.

“Who are you, and why are you doing this to me?”

“Nano Mashin?”

The boy’s face hardened.

Mashin was the deity the Mashin Religion worshipped, along with the Sacred Fire.

The religions’ Master communicated with Mashin.

“Um, are you really Mashin?”

The boy knelt down and asked with a trembling voice. At this, the Nanomachine attached to his cerebrum realized it had been misunderstood.

In a world where everyone changes jobs, I actually awakened to a unique dual career.

And a life-defying career?

High-quality items to cherish? I synthesize directly.

Cherish high-quality skills? I synthesize directly.

Senior pet cherish? I continue to synthesize, wait, how did this beast girl become so big after synthesis?

Let’s start with the synthesis of three skeleton summoning books…

Synthesis – [Undead Army]

Three more dark staffs to synthesize…

Synthesis – [Death Scepter]

The game competition of billions of races in the universe, our solar system, can we earthlings stand on a broader stage!

…

- Description from novelbuddy

In the 21st century Earth gave Birth to greatest genius ever. A genius who Master myriad of arts. Medicine to Engineering. Mathematics to Micro Biology. Weapon Designing to Environmental control. Music to Painting. Dance to Martial arts. He mastered Everything.