Hi! It sounds like you are underlevelled. At what point in the game are you? There are items that increase stats, and triggering adult scenes also gives stats upgrades. There's also a light armor that doesn't have the speed penalty.
Thanks, I spent some times level up a bit and it was smooth sailing until green dragon quest where characters are split up which is troublesome cause I only have gears and levels and skills for 3 characters. One group in particular have no investment at all T_T. Is there a way to finish this quest?
There are weaker enemies nearby you can level with if you can't defeat any of the bosses with the current character stats. Switching the difficulty may also help.
