Eeh... Even though it's not changed from the original (Actually, the original has Tifa guessing she's seven, while the new one says eight) I'm not so sure about Yuffie being that young on second thought - What works for seven or eight, is kind of dicey at five. You might be better just saying the the difference from canon is that Yuffie's a year or two older, so she got a bit farther afield in her search for adventure. I can buy the rest, given that items just kind of condense out of ambient energy to be found in most Final Fantasy games, and that's literally, explicitly how materia form.
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"Anko, what you do in your free time is your own choice. Use it wisely. And if you do not use it wisely, make sure you thoroughly enjoy whatever unwise thing you are doing." - HymnOfRagnorok as Orochimaru at SpaceBattles
woot Med. Eng., verb, 1st & 3rd pers. prsnt. sg. know, knows
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"Anko, what you do in your free time is your own choice. Use it wisely. And if you do not use it wisely, make sure you thoroughly enjoy whatever unwise thing you are doing." - HymnOfRagnorok as Orochimaru at SpaceBattles
woot Med. Eng., verb, 1st & 3rd pers. prsnt. sg. know, knows