The Sailormoon S movie has a fairly simple plot, but the little subplots are what makes it (in my opinion) the best of the Sailormoon movies. The main plot is that Princess Snow Kaguya was sent away by the silver crystal a long time ago and has returned and brought with her another crystal with whcih she wants to freeze the whole planet. Her henchwoman are like little snow women who fly around and freeze everything. I'm sure it doesn't take a rocket scientist to discover who wins the final battle, but instead of staying on that subject, let's move on to one of the subplots.
In the beginning of the movie, Luna who is sick, faints in the middle of a street and Kakeru, a scientist, who happened to find the crystal that the snow queen needs to freeze theh planet, saves her. As her nurses Luna back to health, she falls in love with him. But, alas, this kitty love was not to be for a woman from the space program who loves Kakeru has returned from America just to see him. Kakeru however doesn't like her because she looks at everything scientifically and Kakeru sees the univers in a more romantic way. In fact he belives that there is a princess on the moon which he thinks he loves. To make matters worse, the crystal which Kakeru found is making him sick. In addition to this love polygon we have Artemis who we all know loves Luna.
The princess eventually gets the crystal back and begins to freeze the Earth and Kakeru gets even sicker. Of course, in the end, Sailormoon, with the help of the other senshi, use the holy grial to defeat the princess and Sailormoon gives Luna a little gift - she turns her into a human for one night. Luna in her human form, takes Kakeru up to the moon and there she kisses him. Luna knows that Himeko loves him and so she doesn't see him again and Kakeru make sup with Himeko and Luna with Artemis.
The ending music "Moonlight Destiny" is really very pretty and it's done by a proffessional singer. It's too bad that they only play it at the end of the film when the credits are rolling.