I've only fought it once so far and beat it, but I switched it off because I felt I used too many healing items.
My strategy is similar to the ones already posted, but instead of using ninpo against the mini-boss monsters I just ran straight at them and used flying swallow and it seems to work quite well for me.
I've tried plenty of tactics against those thing so far including jumping away and shooting them with the bow, doing the YYYYYYY attackw with lunar, but so far ninpo is the easiest one, used it twice when i did it on warrior, just saved me from having to use too many potions. But on warrior i seem to be making some serious cash which alows me to buy plenty of herbs easily, as in well over 100k by chapter 6... i do tend to spam UTs though.