For Those who aren't familiar with the series---> http://en.wikipedia.org/wiki/Ys_series .
I love this series and played most of the games mostly 1 & 2, Wanders from Ys, Memories of Celceta, Oath in Felghana, Seven and Ark of Napishtam (the PS2 version of Napishtam is the best version I think). Anyway you play as Adol Christin (aka Adol the Red) who journeys around a world similar to ours but with renamed countries seeking adventure. I got into the series with Ys III: Wanders from Ys for the Snes and Genesis. I didn't play Ys IV or V cause I never heard of them and Ys I and 2 where hard to find in the stores, this is until I played Ys Books 1 & 2 Chronicles. I did play Ark of Napishtam on the PS2 and PSP and to this day I believe the Ps2 version is far more superior, the PSP just didn't have very tight controls.
Anyway my favorite Ys games are Wanders from Ys/ Oath in Felghana and Ark of Napishtam.
Oh the * next to Mask of the Sun means that's the official game although Memories of Celceta booted that from the storyline now.