My suggestion is this. In order to avoid people complaining about Bijuu being "OP", despite the fact that this is an RP driven story-line game, and to avoid people getting "Main Character Syndrome": Split each Bijuu's power among the village it belongs to by a certain number. You could even go by tails, perhaps. For instance, rhetorically, if you make each Bijuu the same relative strength and split it into nine parts, that means each village has nine people that can have that particular Bijuu's chakra. Now, that's just a ballpark number. Nothing to do with any sort of actual balance. But by dividing each beast's chakra up, it makes it so that nobody can go "full Bijuu mode". It also makes it a novelty, but not a particularly overpowering one. On top of that, it means more players can have access to the skill-sets that each beast provides. Once the game's playerbase picks up seriously, this would mean that it'd still be to the point where only a fraction of players had it, and they'd be determined by admins or the Kage of each village, or a combination of both. Just a suggestion, though.