Rebirth of the Useless Bastard Son - Chapter 6

You are the ruler, I am a subject, you want loyalty, I’ll give you loyalty. You are the ruler, I am the subject, you want my sacrifice, I will sacrifice for you. This lifetime, we’ll only be ruler and subject…… cannot become the one who accompanies you to experience everything.

A deposed empress, a failure of a substitute. Charging into battle, he was the emperor, and she, his general. But within the intimacy of their military tent, he was her husband, and she, his wife.

But everything was star-crossed. For the one he loved the most, he would push her into hell again and again.

- Description from Novelupdates

In Ten Heavens Domain, full of respected powerhouses, juvenile Ling Tian accidentally obtained a mysterious iron sword. He refined the Supreme Martial Dao, studied the Divine Spirit Array Laws, fought Ten Thousand proud and arrogant Heavenly Clans, and was undefeated! Seven Feet Sword Tip sweeps away the world, within the Ten Heavens, I am the Supreme God Monarch!

- 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?