DxD: I know…I'm not the real one,just a cheap copy. but...I'd win - Chapter 19: Mittelt’s Feelings and AI from the 3K Era (1)

Ian was an ordinary guy on his way to work when he suddenly found himself in a strange and dangerous world ruled by dark races like vampires, werewolves, and demons. Transmigrated into the body of a lesser vampire, Ian must quickly adapt to his new reality where survival is a constant struggle.Just when all hope seems lost, Ian discovers he has a unique advantage: The Strongest Body Customization System, which allows him to modify and customize his body by consuming biomass. With this golden finger, Ian starts to turn the tables, designing bone claws and other enhancements to give him an edge against the terrifying werewolves and other supernatural threats.But as Ian learns more about the Curtained Imperium and the rigid hierarchies of the vampire race, he realizes that defeating his enemies is only the first step. To survive and thrive in this dark and brutal world, Ian must rise through the ranks, uncover the power of his system.Need to fly? Customize a pair of angel wings!The body is small? Add hundreds meters of height and become bigger than Godzilla!Need a weapon? Customize bone claws and kagune on the spot!

A modern university graduate, traversing the window between two worlds, steals a celestial cultivation opportunity that originally did not belong to him. And this celestial technique, quite unorthodox...My credibility should be assured. In order to be responsible to the readers, I must earnestly remind you: my book is easy to linger on in your thoughts, so proceed with caution.

The Immortal Path led to Longevity and Sovereign was heading in ease. When the Longevity was no longer in ease, all living beings were just prisoners. Conspiracy, internal strife, and the invasion of the others, all of it emerged together. 

In such a world, there was such a young man. He made his way upstream, stepping on blood, defying the emperor, destroying the various kings, and slaughtering his way through the hundred clans to form an Immortal Path towards the throne of Sovereign! The Immortal Path was endless, while the Sovereign was limited. He used his blood to forge his immortal legend.

- Description from Novelupdates

In this world, there is the beautiful mutual and telepathy love.