Hello ! I'm looking for anime or manga with a female character who has a power that surpass others' powers, but she doesn't show it. People may think that she is weak but in fact she isn't.
I want a woman who accepts her power and is not annoying if possible.

For instance, Sonohara Anri in Durarara, Mirajane Strauss in Fairy tail.

No shoujo manga please.
I also prefer (dark) fantasy, but not an obligation

Thanks in advance!

It's a webtoon, but In Full Bloom (YON Jae-Won) would fit I think. It's a (dark) semi-historical setting, not a fantasy.

Sadly I don't know of a fantasy manga like that... but a high school manga with a strong female could be Oresama Teacher

There's a lack of good stories in this area. But yeah, I love them too, manga with strong female characters.

Off the top of my head, I can only recommend Chang Ge Xing - she's frequently underestimated and can be terrifying when she wants to. Very powerful character, with her intelligence and badassery. It's not fantasy or even remotely supernatural, so can't say if it fits. But it does have the historical setting which much fantasy is based off.

There are a few "powerful" female MCs (of the supernatural kind) in a few other manga I've read, but they're all overshadowed by the male characters, so it doesn't feel notable enough to list. no shoujo puts a surprising restriction ahha, but i know where you're coming from with that.

If you're okay with light novels, you could try Juuni Kokuki. A few of the novels, including the first one, focus on a female character who suddenly becomes strong, surprising many people. I loved it. And only watch the anime after, if you're going to - it messes up the story big time. For the novels not officially translated into English, they're not listed on here, but if you look up eugene woodbury's blog, you will find the rest. The translation is very good.

I recommend:
Superior
Akatsuki no Yona
Basara
Red River

Zetsuen no Tempest - isn't the protagonist but shows up later.
Shiori Experience - Jimi na Watashi to Hen na Oji-san rather than a physical fighting power, she gains a musical one. Goes through awesome development.
Kimi Shinitamou Koto Nakare - pretty cool female lead w/ monstrous physical strength that she doesn't flaunt.
Kusuriya no Hitorigoto - again, rather than physical strength, the protagonist is very intelligent and manipulative but tries not show off.