Inheriting a Lost Bloodline, My First Task is to have heirs?! - Chapter 389 - Living Arrangements (Part 1)

I was reincarnated into another world, and I’ve brought the Horadric Cube from Diablo II with me.
Being a knight is cool and all, but being a wizard is pretty neat as well.
So, which one will it be?

- Description from Novelupdates

It was the turn of the 20th century, and in the Philippine Islands, the fledgling Philippine Republic waited to be crushed by the overwhelming superiority of the American colonial forces.But John McClain, a U.S. Army veteran of the Korean and Vietnam Wars, dies and finds himself in the body of the governor of a remote Philippine province in the year 1898. Initially reluctant to take up arms against his former country and skeptical of the chances of success, he eventually decides to fight for the Republic.Now living his second life as Martín Lardizábal, politico-military governor of Marinduque and armed with modern military knowledge, he will change the course of the Philippine-American War.

The world of an NPC born inside an online game was destroyed. Reborn in the real world, he gains a second chance. However, the monsters followed and destroyed he died again. Julian believed everything was over, only to have regressed to the day the game launched. Julian returned to Avalon not as an NPC, but a Player.Avalon's Fall was a VR Online Game created by the goddess.A game to help humans fight back against the six devils. She granted the Players a chance to evolve and enhance themselves in the real world. Because of his fragmented memories, Julian discarded his past. He then focuses on survival and happiness instead of saving the world. There were only two months before the first devil started his attack on the world.Thanks to the perk of his SSS-Rank Class Shadow Mancer and saving his ex-girlfriend, a powerful Sword Master, Julian changes the future. He took a different path, allowing him to surpass anything he ever imagined.Given the power to summon an army of undead in the form of shadow warriors. He overcomes the demons of his past. Supported by his party, they struggle to survive in the collapsing world, desperate to survive.The Devils eventually discovered his true potential and focused their gaze upon Julian. A title given to one existence, he who would rule over all darkness. The Heir of Shadows. The 13th Divine.Erebus.

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?