Well...Certainly a straightforward title.
"Make up the rest of your rent by having sex with me", plus it's only 30000 yen a month? Sounds like paradise.
Every month, though...I wonder if they could work out a system where he has sex with her everyday and then gets to live there for free?
Hmm, ... IRL, high risk of later having to "Go See The Doctor" (if-you-know-what-I-mean) plus potentially jealous rivalries among the members of Landlady-san's reverse harem.