Hajimete wa Zenbu Kare no Gochisou

Kouki Suzuhara is a college student who still hasn't slept with anyone because he's too scared to date girls. He's sobbing at a bar after getting jilted again when a stranger tells him that he'll introduce him to a girl. He's light on his feet as he goes to a designated room... and who does he see smiling wickedly with a rope in hand but Masumi Shiina, the stranger he met at the bar!! "You'll still be taught the beginner's course... by me." From that day onward, the stimulating lessons get underway...!! And so begin the all-out tactics of love with a pushy, yet irresistible older man! Don't miss this explosion of heavy romance.

(Source: Renta!)

Included one-shot: Seishounen Paradox