Chronicles of Forgotten Extra - Chapter 25: The Sword of Chaos

A 30-year-old NEET is reincarnated into the body of an otaku that choked to death on instant noodles. As he comes to grips with his new life, he realizes that this world is subtly different from Earth. The denizens of this world are far better looking, and this new world also possesses futuristic technology as well as mysterious Yin Yang masters!

Roan, ran away 20 years ago from his rural village in the aim of becoming a Great General. However, all he got 20 years later was just a handful of money and the lowly position of squad commander of the First Legion’s.

The leaves of the chess game beside Lanke, and there is no one playing chess among the old trees
Xing caused Tian Yuan’s first son, and then looked back at the vast mountains and seas
When he woke up, Ji Yuan became a half-blind beggar in a dilapidated mountain temple.
A real person has a sword and a magic stick has a mouth, which is the foundation for Ji Yuan to settle down in this terrifying world.

- Description from novelbuddy

The young lord of a small and weak country saves a dragon beside the sea one day.