There was this manga I read (Shoujo or Seinen) where the main character is this rich guy that always gets kidnapped or targeted by assassins so much that he finds it to be normal and doesn't even flinch anymore. The girl is the new maid (red hair I think) but she's clumsy and is secretly his bodyguard.

The guy pretends to be weak and defenseless but he's actually strong.

Anyone know what it's called?

This one? Kimi wa Boku no Toriko Nare
The girl is not red-haired though.

Try Crimson Empire. Its a reverse harem so not for me but if you like the stuff then that should be fine. She is a redhead too.

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Manga/Anime. Philosophy, Poetry, books, basketball, russian rock.

Try this: Tokyo Crazy Paradise
but the guy isn't weak..

Grand Sun?

I agree, I think this is it. But the girl has brown hair

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“I thought also of another thing between us. Call it trust... That is one of its names. It is a very great thing. Though each of us alone is weak, having that we are strong, stronger than the powers of the dark.”

Grand Sun

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http://westsiders2.deviantart.com/

maybe crimson empire? meets almost all of the criteria... if its not im still looking

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Hey there~! wanna find a manga? if so i can help you out most definitely! just say the plot and ill rack my brain for it! i love finding series for people >.<
btw if you read fanfiction check me out purease https://www.fanfiction.net/~animegirl101100 I love getting reviews.
*Honest Walker*

No its not Crimson Empire, I've read a few chapters of a manga that exactly fits your description, however I'm sorry but I stopped after a few chapters and now I can't remember the name .