From the Start, I Have the Eye of Kenjaku and Can Conquer the Western Fantasy World

[Possibly a harem, or no female lead; no power struggles; overpowered protagonist.]

After transmigrating into a Western fantasy world, Gray is put at ease when he awakens the innate ability known as the Eye of Mimicry from the start.

The extraordinary world's battle aura and magic fill him with longing.

With the Eye of Mimicry at his disposal, all Gray has to do is see someone use a skill once to learn it without a teacher.

One glance, and he knows it. One glance, and he understands it.

And the story begins when he becomes an adventurer.