The health of nine tails is self adjusting, if it dies too quickly, it will grow whereas if it doesn't die quickly enough, it will weaken. This was needed due to population difference between servers.

That said, for some reason unknown, the starting hp for a new server is 1000, as opposed to some more reasonable amount, so this happens. There have been many complaints about it but nothing ever done, personally I think it should start at 100k to 5m, thou I'm no expert on how much damage new server can do.

Hey

It's not a bug.

Ninetails will passively scale up with age. Your server will get a stronger Ninetails in due time.