Well, if you're looking specifically for Cannibalism, I can't help you here. If you're looking for what the threat title says though, a story in which the MC is reincarnated into a very different culture, I'd say "The Rincarnation of Alysara" does an excellent job. That thing's got a hermaphrodite culture that practices open bathing and is tribal in nature. It's pretty fun.
After being reincarnated as a busty fox-like race in a fantasy world filled with magic and mysteries Alysara finds herself blinded after getting a cursed skill. Now she must train her ability to sense the mana around her and discover what mana and magic really is to see. There is...
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I don't quite do as good a job as Alysara in terms of portraying a vastly different culture, but I'd pitch my own series, Key to the Void (link in signature) for this as well. My elves keep humans as pets so they can suck the energy from them. The MC is reborn as an elf. 2 other reincarnated people are reincarnated as humans. MC's parents captured these other two and gave them to the MC.
As for how that plays out... well... it's not that my character
doesn't go all energy vampire on them... it's just that she found a far tastier source of energy so she doesn't have to eat her friends.
... Ok, I guess somehow my series sorta does answer your criteria. It's just that my MC cheats her way out of it.