A year after the events of Fushigi Yuugi, Tamahome is pulled back into the book and is sent on a complicated ride through illusion, confusion, and betrayal. Meanwhile, Yui is acting oddly and Miaka is heartbroken over the loss of Tamahome, while Keisuke and Tetsuya try to discover what is going on with the book. (Source: ANN)

The story centers on Nayu, a middle school girl who shocks her schoolmates on the first day of school by wearing black lace panties. She likes this kind of underwear, and she tries to "spread the word on the merits of [these kinds of] underwear" via an underwear club with her schoolmates, who are worried about their bodies' development and which underwear to choose.

Meet Galan, a Russian spastic geek who`d do anything to be a real, live samurai. But that`s just an impossible dream... or is it? When his friend Natsu, who is a successor of Japanese emigrants family, gives him the gift of an ancient sword, strange events unfold, and even stranger people drop out of the sky to attack. Now Galan must overcome his ineptitude and join a bunch of beautiful women in a wacky romp through a kingdom that time forgot. Hey, what could be better?

Lupica, another one of the legion of space princesses that all seem to have found out about Earth in some tour book, appears and abducts Ataru! 

But Lupica isn't after Ataru for his great looks or charming personality (because he doesn't have either). Lupica's goal is the greatest love potion in the galaxy, which she intends to use to induce her sweetheart to tie the knot. To get it, she needs the possessor of the greatest lust in the universe...

(Source: AniDB)