In my experience, there are about two areas that seem to be bottlenecks of grinding.
The first is the ant-lion boss. The second comes about halfway through the game, against a bird boss. One or two levels is usually what it takes. It's kind of annoying, though on the plus side, after that stat boost, the difficulty settles down quite a bit. The game is a little wonky with how it balances things.
The sequel, Janen no Jishou (I've only played the Japanese version), doesn't seem to have any thought put into its difficulty (it's braindead easy). It's also an incredibly shitty game.