Anime you would recommend to a fan of this series

I'm not big anime fan, but I do enjoy some of the art styles and I'm looking to get into anime a bit more. I remember watching this series on nights when I couldn't sleep on G4, back when they were still airing anime unleashed. I loved this anime and most of the characters in it, Hisami was annoying. I ended up recording the episodes for nights when I actually could sleep, and I watched the whole series. So are there any animes you would recommend to a fan of this series?