Kimi wa Kokan no Mochigusare

Handsome, nice and smart, but Kaname Kusakabe gets dumped all the time because of his unusually large male organ. He decides to go to counseling. Doctor Minato Momose is extremely sympathetic to Kaname's dilemma. "An impressive specimen, but he's never been with woman!!? I have to help him!" As a doctor, Minato can't help be curious about Kaname's oversized organ. After having it poked and rubbed... Kaname can't help exploding all over the doctor's face. Minato doesn't mind at all, though. He's actually very excited...!

(Source: Renta!)