I'm looking for stories where one female and two (or more) males are involved in a relationship. I would prefer something with an actual storyline, not just sex. The closest thing I've found is the one-shot Monkey Strip. Any suggestions?

Are you looking for a "reverse-harem"?

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Yes and no. The typical shoujo might have more than one or two guys liking the same girl, but in the end she has to choose just one. I'd like something where the girl chooses to be with both at the same time.

Try Aisuru Hito, it's not completely scanlated so she may choose one in the end, but not yet...

Also the first story in Furachi na Otokotachi, and maybe Love Scar.

"[English] not only borrows words from other languages; it has on occasion chased other languages down dark alley-ways, clubbed them unconscious and rifled their pockets for new vocabulary."
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Princess Hanaka by Kayono might be something you're looking for. And I totally second Aisuru Hito.

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S+M seems to be something like what you're looking for.

Thanks everyone! I'll check out all of the suggestions.