Ys I in particular has some rather obnoxious design in many ways, such as how the latter 2/3 of it is played. You'll see if you get there. Upside is, the level cap is only 10. Though that's in part to make sure you're all maxed out before the 3rd boss and final dungeon due to uh, well again you'll see what I mean.
Ys II is a fuckton better in every way, which seems odd given that the two of them were originally meant to be just one long game. The addition of a projectile attack alone improves the combat and bosses by a lot. In fact, all but the final two bosses require the fireball and its homing upgrade. Its probably the only boss rush in the series I'll come back to just because they're so damn fun. The bump combat is also easier because enemies will pretty much do nothing if you just run at them diagonally. Though that doesn't work as well on Nightmare difficulty. Also you can set villagers on fire. Or gift them flowers and [parasitic bomb] to the point that they blush whenever talked to.