Japanese - Kimi Wa Petto & You're My Pet is the Korean movie version
taiwanese - My Queen is the original of Witch's Romance (I haven't seen the Korean one yet) 
Korean - Queen of Reversals & I think Scent of a Woman was a noona romance with as light age gap but I can't remember for sure
Long Vacation
Cheap Love
Madame Antoine that is airing now - there's three younger guys ^.^
and an older jdrama Love and Eros with Nagase Tomoya (the video quality isn't even good since it's from 1998, but I like it)
Sore wa Totsuzen Arashi no Youni - with Yampi