Mao Sugiyama had his penis and testicles surgically removed in March and kept them frozen for two months before dishing them out -- seasoned and braised -- to customers at an event hall on May 13, according to postings on his Twitter account and local police.
Diners paid 20,000 yen ($250) for the plate with a portion of genitals. Pictures published on a website appeared to show the meal came complete with mushrooms and a parsley garnish.
The painter, who is reportedly 22, said on Twitter the organ had been removed by a physician and certified to be free of infections.
The meal was prepared under the supervision of a certified cook and diners were required to sign a waiver indemnifying Sugiyama and event organisers.
In May 18 tweets, the artist said steps were taken so the act met all relevant laws, including a ban on organ sales, processing of medical waste and even food sanitation requirements.
"I receive questions from some women and men... asking 'Will there be a next time? Please host it again.' But there is only one set of male organ," he tweeted on May 16.
"Unfortunately, I have no plan for the next time."
Sugiyama, who considers himself "asexual", that is without gender, initially thought about eating the genitals himself, but decided to solicit paying customers to help pay his hospital bills for the surgery.
In an email to AFP, he confirmed the event had taken place and said it was organised to raise awareness about "sexual minorities, x-gender, asexual people". He said he was readying to publish an official account of the day.
Police in Tokyo said they knew of the episode, but added that it had not broken the law as cannibalism was not illegal in Japan.
"We are aware of the case. There was nothing (criminal) to it. It does not violate any detailed rules. There is nothing to take action about," an officer at Suginami police said.
Sugiyama sparked a firestorm of interest on April 8 with one tweet:
"[Please retweet] I am offering my male genitals (full penis, testes, scrotum) as a meal for 100,000 yen …Will prepare and cook as the buyer requests, at his chosen location."
On April 13, five of six diners who signed up for the $250-a-plate feast, sat down to dinner. The sixth person was a no-show.
The next day, an organizer posted a blog -- subsequently deleted -- containing pictures of the event. Images showed dozens of people who attended the event just to catch a glimpse of the rare treat.
The extra diners were served crocodile-based dishes while Sugiyama cooked up the exclusive meal.
The story went viral in Japan. Some showed even more interest, while others complained. But Calorie Lab called Japanese authorities, who deemed the banquet legal because there is no law against cannibalism in the country.