Torotoro Seikan Massage in Bunkasai!

Satoshi meets and subsequently deceives a girl into letting him give her a slippery, erotic massage, rubbing her from head to toe... and then thrusting her over and over with his hot member, "loosening" her up from deep inside!
(Source: Coolmic)
Note: Simultaneously released in long-strip and traditional formats, with 6 episodes and 2 chapters respectively.