MTL - I Had a Home In 1982 - Chapter 1 End of the World Island

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

A novel revolving around being transported to another world with an op system. The mc spends his day chasing skirts and doing missions to level up. A standard journey to the top with lots of girls from various animes and games with a twist of that gaming feel (hunting mobs, doing missions).

- Description from novelupdates

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.

[I am the seventh generation Nanomachine manufactured by Sky Cooperation, and I am operating as a central nerve connected to your brain.]

“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?”

[“I am the seventh generation Nanomachine.]

“Nano Mashin?”

[Yes, Nanomachine.]

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.

I don’t know why I die, I don’t know why I live.

Divided hunters die of loyalty,

The witch who plays with emotions dies of love,

Cautious fortune-tellers die of trust.

The thief who steals everything has nothing,

The visionary who created everything never existed.

The traveler fell on his way home,

The twilight giants rest before dawn.

Lawyers sacrifice for order,

Judges forget the law.

The sleepless sleeps in the dark,

The corpse collector lay in the coffin.

We are guardians, and a bunch of poor creatures who are constantly fighting against danger and madness.

This journey is life and death.

While drowning was inevitable, they had struggled.

This is the worst of times, this is the best of times.

- Description from novelbuddy