Hmm... what about nazo no Kanojo X (mysterious girlfriend X). Except for he scissors she isn't rally sadistic though, although her form of torture is more like being 10 steps ahead of the MC
Legend of the legendary heroes (Densetsu no yuusha no densetsu) has a sadistic character as an importan sidekick
Ookami-san to Shichinin no Nakama-tachi: If I remember correctly two side-characters are in a sadism-masochism relationship, as well as the female lead having a slightly sadistic side.
Horizon in the middle of nowhere: it's not that the female characters are sadistic, they just treat the MC sadistically
Baka to test series again has two secondary sadistic characters, as well as a more important duo
Goshuushou-Sama Ninomiya-kun: The entire female student body ganging up on an protagonist has to be considered sadistc
Ah my buddha! series, though it's mediocre
Desert punk: I'm not really sure about that one anymore, but I seem to remember that teh antagonists treats teh punk sadistically, although that's a side-plot at most
Pumpkin Scissors: Dat nurse
(Only side-plot and totally unintentional, but for a man it's seriously sadistic)
Anyway, don't take those recommendations too seriously, since most of them only feature the intended character as a side.
