Sakka to tsuma to sono aijin (2002)

Tomizo Hatomune is a writer who has racked up massive debt through his womanizing ways. A loan shark named Samehada offers to wipe the slate clean if Hatomune agrees to take in his mistress and look after her at his home. Hatomune accepts the woman—named Hiroko—as a live-in helper, only to discover that her voracious appetite belies her innocent, lovely appearance. Smitten with lust, Hatomune constantly looks for a chance to seduce her behind his wife's back...