In Great Teacher Onizuka, many people sees Urumi Kanzaki as a better choice for Onizuka. Maybe the fact that she does have a personality helps, while Fuyutsuki is there just to fill the role of love interest.
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Quite a few Genshiken fans would love to see Madarame and Saki at least try to get together. Sure, Madarame seems to have a disadvantage compared to Kousaka in the looks department, but he and Saki seem to be a much better match when it comes to temperament. They also like to tease each other a bit too much for comfort.