His Contractual Mistress - Chapter 487 Only Belongs To You

Who could have guessed that the accidental discovery of a pitch-black USB drive would one day turn Chen Chen’s world upside down?

This is the story of Long Yi, who was killed because he took revenge for the girl he loved. Before he dies, a strange lightning carries his soul into a different realm. How will he live, when the first thing he noticed upon arrival is that, the man whose body he possessed is raping the country’s princess?

- Description from Novelupdates

Long Fei, a cross-timer and doujin, is an otaku who traveled to another world. In the original world, he was an otaku fan of Gundam and military science fiction.

He died in an accident and was reincarnated into another world. The Gundam works he had read before his death and the techniques in various military novels could be brought to another world.

How would he use the Gundam that Long Fei created? What waves can be caused in this different world?

- Description from novelbuddy