An oreimo is a male that has a lot of girlfriends, but dumps them all to marry his sister.
"Don't end up like an oreimo."

"Look at that guy, he's an oreimo"
by Tobiichi Origami January 27, 2014
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I f you enjoy Oreimo then GET THE FUCK AWAY FROM YOUR SISTER!!!!!
by Dragonbrine12 September 9, 2017
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