MTL - My MCV and Doomsday - Chapter 3 Scan and retrofit

Cassian Ven Dyke, the bastard son of a powerful ducal family, grew up in the slums of Veldora under the care of his father figure, sword master Russel. When Russel passed away, Cassian was left with only a silver necklace as his inheritance. After putting it on, Cassian was attacked by three psychotic thugs who tortured him in an attempt to steal the necklace. Refusing to give in, Cassian was ultimately stabbed through the heart with the very same necklace. Instead of dying, he mysteriously vanished as the necklace lodged itself in his heart. Just before disappearing, he heard an eerie message echo in his mind:[True mana detected. Origin: Human...][Human detected. Compatibility with system: Confirmed.]

Transform into Divine Dragon and dominate the world!
He is the only Divine Dragon in the sea who founded an underwater Dragon Palace.
With Crawfish Soldiers and Crab Generals as his followers, wild sharks and gigantic octopuses as his subordinates, he is the dragon that rules the city.

- Description from Novelupdates

Perfect. That’s what people call Princess Elysia. Blessed with rare red fire magic and trained by the best, she’s the shining jewel of the kingdom of Arvandor. But perfection has a price. When the ruthless Demon Queen Malvoria sets her sights on Elysia, all hell breaks loose—literally.As Malvoria’s army lays waste to Arvandor, Elysia’s life is shattered. Her beloved father, the king, is slain, and her once-peaceful home becomes a battlefield. Forced to flee with her girlfriend, Zera—the fierce daughter of her magic teacher—and her mentor, Lady Seraphina, Elysia’s journey of survival begins.But Malvoria wants more than just a kingdom. She wants Elysia, and nothing will stand in her way. As Elysia’s hidden powers awaken, an unexpected and dangerous attraction sparks between her and the demon queen.

An otaku with a hobby of masturbating was reincarnated as the son of a great mage.

As soon as he was born in this life, he vowed with a goal of embracing women till his death.

That said, when he became 20 years old, the Demon Lord which was sealed by his ancestors revived, and now it is his role to seal it once again.

And that demon lord is sealed in a tower dungeon that is rumored to be impossible to capture.

However, by an unexpected coincidence, he had found out that the Demon Lord is also one of him, a kindred spirit from within,

so he joined her instead and filled several traps in the tower dungeon, and thus they enjoyed a s*x spree with all the women coming over!