MTL - Demon Slayer Starts From the Proficiency Panel - Chapter 33 [033] Daoist painter, Qingluan Yutian

Shao Di Yu, an orphan, is adopted as a result of of a murder case involving the deaths of his entire family. Because of some painful experiences, he refuses to speak. However, he has sharp insight; moreover, he becomes under the care of a pair of twin brothers in the police force, who also have a child currently in university. Yu Yin possesses yin-yang eyes, which allow him to see things ordinary people cannot. The two brothers happen to complement each other, and together they investigate various inconceivable incidents.

King Grey has unrivaled strength, wealth, and prestige in a world governed by martial ability. However, solitude lingers closely behind those with great power. Beneath the glamorous exterior of a powerful king lurks the shell of man, devoid of purpose and will. 

Reincarnated into a new world filled with magic and monsters, the king has a second chance to relive his life. Correcting the mistakes of his past will not be his only challenge, however. Underneath the peace and prosperity of the new world is an undercurrent threatening to destroy everything he has worked for, questioning his role and reason for being born again. 

Cultivating his power by slaying demons and taming countless beasts, the emperor solidified his throne as the world's ruler. But not once in his life had he expected that his disciples would use research on demonology to sap the world tree's power and push the world to destruction.Trying to fix his mistake, he opted to use all of his cultivated power to cure the world tree and block anyone from sapping its power ever again. But in exchange, he was to lose all of his power.But...the worst had happened, his wife... had betrayed him.

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?