In her mouth.

Shoko paused and let Kenji blast her throat with thick gobs of semen, barely giving her a chance to guzzle his load before her mouth was full again, for almost a minute. When he finally stopped, she continued stroking his shaft and squeezing his balls, trying to milk more jizz from him. Satisfied that he could give no more she popped his cock head from her lips, licked it clean, and gave it a kiss.

"Very impressive, Mr. Kataoka," the young doctor smiled at the still rock-hard erection in her hand. "Now we know you can ejaculate, at least with fellatio. So we can rule out the physical cause of obstruction ejaculatory ducts."

Kenji nodded weakly, still recovering from his first blowjob.

"That said, we still need to know if you can ejaculate from other methods of stimulation."

"What do you mean other methods, Dr. Sugimoto?" he asked with curiosity.

Shoko smiled at his perked interest.