Behemoth's Pet - Chapter 105: Onward To Lumilus

Rainer, an amateur arcanist and college student, sought to create a new spell far surpassing the magic of the few he inherited from his grandfather. Yet the interference of an unknown event during the casting of his spell led him to be thrown through space and time.

In a world dotted with World Entrances to a demon world, demons have invaded humans for centuries. Humanity has united and one of the most ancient sects in the world, the Archean Mountain Sect, has set up an entire education system in the form of Dao Academies and defenses at the World Entrances.

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!

After his girlfriend broke up with him, wandering all over the place, Xia Tian happens to see a girl about to be hit, after he saves her, he ends on the hospital. Now thanks to his accident Xia Tian awakened the ability to see through anything, be it weak points, or through clothing, nothing escapes his eye. Especially girls.

- Description from novelupdates