Saragaga

“Look, boss, that red dragon lacks dragon's might, and it doesn't even know how to breathe fire. Let's take it down and make a fortune,” said one of the adventurers. 
At that moment, the lethargic red dragon opened its eyes, looked at the adventurers appearing before it, drew a forty-meter sword, and deployed techniques such as Sword Mastery, Samadhi True Fire, Eighty Nine Mystical Powers, and Law Heaven and Earth...

The world became quiet again, and the red dragon rolled over and continued its nap.

This is the story of a red dragon who, after years as an overworked employee, finds himself reincarnated in another world. 
Devoid of the intrinsic knowledge and natural abilities of dragons, it wields other formidable skills.

Chapter 424: Visitors from the Star Realm