Are there other ways of purchasing Crystals apart from buying them in the game?

The only way of purchasing Crystals in Hello! Brave Cookie is buying them from
the in-game Shop using iTunes or Google Play billing methods.

You might encounter third-party sources that offer you Crystals in exchange for
your Game Center or Google account information.

If you provide your personal login information to third parties, we cannot guarantee
the security of your account.

We cannot provide any support for problems that stem from the purchase of
Crystals from third party sources.
Please also be aware that this is considered a violation of our Terms of Service and
sufficient reason for suspending your game account.