In my opinion, Kaze To Ki No Uta (Song of the Wind and Trees) is an anime (adapted from a manga) that every shounen-ai fan should watch. Although it has relatively little sexual content, and was made as an accompaniment to the manga, the artwork and the story are timeless and beautiful.
The anime opens with an adult Serge Battour visiting his old high school, and going into the room he used to live in with his roommate. Almost exclusively in flashback, the story goes that Serge Battour, a young half-Roma viscount in 1800's France, goes to a new school, where he encounters Gilbert Cocteau, a wild and promiscuous student. He and Gilbert are roommates, and he soon learns about Gilbert's activities in the school: trading sexual favours for term papers. As this is 1800's France, homosexuality is deeply frowned on, and the only reason Gilbert is still allowed to attend the school is because his uncle is a primary benefactor of the school. Serge makes it his personal duty to try and reform Gilbert and make him accepted by the rest of the school, but along the way he and Gilbert develop more than friendly feelings for each other. Upon realising their romance will never be recognised in school, they escape to Paris where they live in poverty for a time. At some point, it is revealed that Gilbert's mysterious uncle sexually abused Gilbert from a very young age to the point where he didn't know how to express his feelings except through sex. In desperation, Gilbert turns to drugs, then throws himself under the wheels of a moving carriage and dies. The anime ends with Serge leaving the school.
I absolutely love the artwork for both the manga and anime. Although it is from the 1980's and admittedly clunky, the characters are so beautiful they appear sexually androgynous throughout the entire anime. The music for the anime is stunning and sets the tone perfectly.
The characters are the best part of the anime. Serge is the typical boy who fights against the racial prejudice of being half-gypsy and tries to reform another human being out of the goodness of his heart. He is the only 'pure' character in the film, being completely without prejudice against anyone. His romance with Gilbert is equally pure - he resists Gilbert's advances until he feels willing to accept them romantically, not just as a declaration of thanks or as a trade-off for being nice. Gilbert is a very interesting character. He is troubled, has a dark past, has a gorgeous character design, and is possibly one of the best shounen-ai characters I've come across in a long time. His work as a prostitute only serves to make him a more convincing character, and all the harder to reform. Other than Serge and Gilbert, all the other characters are pretty inconsequential, although there are a few gems.
Overall, this is a must-watch and a must-read for all shounen-ai and yaoi fans. It is one of the oldest and most fantastic examples of shounen-ai ever produced.