LUNAR Walking School (so called, I'm guessing, because the main characters do an awful lot of walking) is the one LUNAR game that has never seen an English release. It's a bit different from the main storyline; it's more lighthearted, there's no major world-destroying disaster pending, and there aren't any continents to traverse, only really the small island on which the school resides.
Said school, incidentally, is not Vane. This confused me when I first played the game in Japanese - the kids walked onto an actual island in the sea, and here I am thinking "What the hell, Vane flies in the sky!" Turns out it's Iyen, a sort of sleep-away high school to Vane's college. It still moves around in the ocean, but you never actually see this - you're just told that it moves, and new bridges occasionally show up when it's "near" certain places. It is this school to which our main characters Ellie and Lena are sent at the start of the game, and where they spend most of the duration.
The game, in my opinion, is just so-so. The battles are as fast as they can be (made slightly slower by menus that take longer to draw than necessary) but the encounter rate is hair-pullingly bad, especially later in the game. It's unfortunate because the creators really drilled the importance of magic as a battle tactic into the game; there are plenty of ways, both active and passive, to recover MP, and your spells are MUCH more powerful than your physical attacks. It's nice to see a battle system where wizards are something more than healers or boss battlers, but the encounter rate dampens that feeling substantially.
Insofar as any actual plot is concerned, for the most part each chapter is a stand-alone story. On the upside, this means that the game is extremely episodic, and can easily be picked up from where you left off, especially if it's at the end of a chapter. On the downside, this means that the game can feel rather disjointed at times, and the overall plot basically boils down to "The Vile Tribe is bad and nasty and is causing problems!"
It's still a decent game, though, and is worth a try if you're a fan of the series!