Inkya JD Saimin de Chinko no Shihaiken Ubawarechattara, Shin-chan Nan ni mo Dekinai ne?

"My introverted and gloomy childhood friend who I looked down on, now controls my orgasms through hypnosis and I've completely fallen for her."

When a plain and introverted college girl named Hitomi Shiina was reading a book about hypnosis techniques, her extroverted childhood friend and college boy named Shinji Nishina came over to visit. He finds it funny and while making fun of her, he let her apply the hypnotic techniques on him.

Shinji thought nothing had happened to him, but when he was about to have sex with his girlfriend, he was unable to get hard. However, his libido was unaffected and it increases to the point that he's losing control.

When he rushed to question Hitomi who placed him under hypnosis, she tells him:
"You can't get hard or cum without my permission anymore, okay?" and she smiles like she's triumphed over him.

"Hey, should I let you cum? Show me how you beg in front of this gloomy woman you've always made fun of."

If she tells him "You can't cum", he's unable to ejaculate, and if he's told to "Cum for me" then he can't stop himself from ejaculating. No matter how many times he's ejaculated, with one phrase "Get hard" from her and he'll be able to cum again.

Right there is his introverted childhood friend, showing him a sadistic side of her that he's never seen before, until now.

(Source: Melonbooks, translated)