They're both yaoi manga involving a gorgeous, well-built up, muscled, rich and increadibly successful guy (your ideal man in short) who falls for an untamed, naive guy who thinks he can escape his claws.... <3 Great story, great art, great manga; totally worth them!
Kuroneko Kareshi reminds me of the second story in Leopard Hakusho. Both are told from the perspective of a long-haired character who is both promiscuous and naive. No matter how long it's been or how many people you've slept with, you can still be hit hard by your first love, is the premise? In Kuroneko Kareshi the long-haired protagonist is the uke and in Leopard it's the seme, though. They're stories about true romance breaking through what on the surface is a purely sexual relationship. It's a struggle for both seme to overcome the uke's insecurities and get them to commit to romance.