Eroica Yori Ai wo Komette is one of the few mangas that can be classified as both shounenai & BL because of how long it's been in publication. Starting in 1978 & still being written to this day.
When writer Aoike Yasuko took a long break in the 90s doing gawd knows what, she picked the story up again with a different art style. She actually managed to convert her art from retro to modern (sadly), & the fans still wait to see if Dorian will ever get Klaus, hoping to heck it doesn't end abruptly like her amazingly funny series; Ibu no Musukotachi.
If you're a BL/shounenai/retro manga fan, you've GOT to add her stuff to your collection!