Ar Tonelico: Melody of Elemia.

Let's see, protagonist is stereotypical hot-blooded idiot hero with awful memory, gets to meet shy yamato nadeshiko type and "emphasis on tsun"-dere pettanko under fairly contrived circumstnaces, both of who are strongly attracted to him for initially ill-defined reasons, and is given a mission to save the world. Hmmmm...well, it kind of hurts the brain, but I haven't actually lost interest due to any of that, so...I'm still playing it, I guess? It's not like I've gotten much past the beginning yet, and it's also giving me a strong Mana Khemia/Atelier vibe, which is unsurprising considering that it's from Gust.