I, the Weakest Human, Start with a Hundredfold Bonus Talent！ - Chapter 127 - -Red Dragon Drystan

After Reincarnating into Naruto World at the Warring State Era as an Uzumaki, Masahiko thought that he got a useless System. He lived for 48 years as a normal, below average Uzumaki Shinobi.

That changed when he finally knew how the system works the day of his 49th Birthday!

- Description from Novelupdates

I originally thought this was a world like an ordinary urban novel…Drawing comics by myself, traveling is pretty good.
But tell me, what happened to this magician called “Emiya Kiritsugu” who jumped on my face?
Who changed the settings?
Currently involved in the content of “F/Z”, “F/SN”, “Fantasy Carnival”, “The Emiya’s Meal”, “The Holy Grail of the Imperial Capital”, “FLA”, “Elmello II Event Book”, “FGO”, “FE”, etc.
Others related to “JOJO’s Bizarre Adventure”, “Rebellious Lelouch”, “Persona 5”, “Attack on Giant”, “Death”
“FGO”, “FE Series”, “FA”, “FSF”, “Cangyin”, “Magical Girl Illya” will be involved next…

- Description from novelbuddy

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?

Corporate slave Alexander dies with only one regret—not finishing the fantasy novel in his hands. Fate has a twisted sense of humor when he awakens as Alexander Flamingo, the perverted villain destined to be expelled and killed in that very story!Armed with complete knowledge of the original plot and a mischievous “Harem King System,” Alexander plans to rewrite his fate. No longer the one-dimensional pervert of the novel, he'll use his future knowledge to manipulate heroes, seduce heroines, and rise from disposable villain to the true mastermind of this world.The system grants him power through every relationship he builds—but can this calculating reincarnator use his second chance to avoid his predetermined death and become the ultimate Harem King? One thing's certain: this story won't follow the original script.