Kichiku, Encount

Meet hard-working systems engineer and wage slave Hajime Sato, age 25. He's on his way home after pulling an all-nighter, harsh sunlight flooding the early-morning train car... when he hears the moans of a porn actress (insta-boner!). Wondering what kind of loser virgin's playing porn on the train for all to hear, Hajime looks over to find that the guy seems like a real playboy... To apologize (!?) for his unplugged headphones making Hajime hard, the handsome stranger takes him on a journey to lose his virginity... His anal virginity, that is!
(Soure: Renta!)
Note: Includes an extra chapter and the one shot "Onegai!! One Night Stand (お願い！！ ワンナイト・スタンド , Please!! One Night Stand)".