Re:Zero Kara Hajimeru Isekai Seikatsu - Arc 6 – Chapter 84, “Heave-ho! Heave-ho!”

Duwei is born in this new world from Earth without making any sound, he does not cry, he just stares at the people around him. As he grows he does not speak and curses this new world in which he is forced to live.

His father a great general of insurance he must have aptitude for something, nevertheless he is not more than trash. Ignored by his family as the “Retarded” heir.

This is the story of your journey to discover the truths of this world and use the knowledge of your past life to remove your title of retarded, even if you have to become a devil.

Until he became the lowest-ranked master, his lonely and luckless life never changed.

Suddenly one day, a descendant injected him with a nanomachine, and the machine started ‘speaking’ to him.

“What? What are you talking about?”

This was beyond the boy’s knowledge, he turned pale.

The Nanomachine linked to his cerebrum realized the User was not understanding a single word it said.

“Who are you, and why are you doing this to me?”

“Nano Mashin?”

The boy’s face hardened.

Mashin was the deity the Mashin Religion worshipped, along with the Sacred Fire.

The religions’ Master communicated with Mashin.

“Um, are you really Mashin?”

The boy knelt down and asked with a trembling voice. At this, the Nanomachine attached to his cerebrum realized it had been misunderstood.

“Married rich for three years with no child born. Just when she was finally cured of infertility and ready to give him a child, he brought home his pregnant mistress in high profile.

“”Get lost if you can’t get knocked up. Or do you want my son to be the last of the Mo family?”” her mother-in-law viciously cursed.

Her husband grimly shoved a divorce agreement upon her face, “”I’ve signed. Leave when you are ready.””
It was heard later that two men went physical in the city plaze of Ye City to win back the wife, with the two babies at the side fighting fiercely for their mom!”

- Description from Novelupdates

There are a total of seven sins, and a revelation is made to a young man named Alex that he is destined to become a demon lord, more especially a demon lord of sin called LUST.

It's not like he can change that and because he always knew something about himself was different—not in a physical sense, well, maybe a little—and not in a mental sense—but rather because he is thrown into a demonic war that compels him to accept his new reality.

He was only aware of a difference in himself. Relating to him and the ladies who are drawn to him... Well, it was more or less like he was a magnet in front of all the girls, and all the girls were drawn to him like a metal.