Based on the erotic game by 14rabbits.

After college graduation, Tanaka Daisuke started working and living alone. Even with the cheap, small, old, and untrustworthy boarding house ads, Tanaka-san immediately leaves his old boarding house. What makes him interested in these ads? If he pays the boarding house money on time, he will receive a special service from the Land Lady. What might that special service be? Having sex with the Land Lady with the small body of a child.

(Source: Translated and Edited from Nekopoi)