A Tokyo association of university cooperatives is now selling students what they truly want - "tan-i," which usually means school credit.
The catch, however, is that the new hot-selling item, marketed by the Tokyo Business Association of University Cooperatives, is a cream-filled bun.
Two kanji characters that make up the word "tan-i" are branded onto the surface of each bun.
Though it is a corny joke as an answer to students' joking requests for co-ops to sell academic course credit, the buns became extremely popular among university students busy taking examinations and writing academic reports ahead of the end of this school year.
The association began selling the buns in more than 60 stores run by university co-ops mainly in Tokyo, and in many of the stores, the buns sold out.
The buns are so popular that the association increased their production.
With a custard filling, the buns go for ¥108 (S$ 1.20) each, including tax.
The stores stick to the joke and only write on receipts: "Tan-i - ¥108."
The university co-ops receive cards on which students write their requests, and there were a sizable number of requests for co-ops stores to sell academic course credit.
In November last year, about 10 store managers and other employees of the co-op held a meeting to discuss product lineups and decided on the "tan-i" buns.
Hoping the buns could somehow help students with their studying, co-op officials in charge of the products said a prayer at Yushima Tenjin shrine in Bunkyo Ward, Tokyo, over the hot irons that brand the kanji characters into the buns.
The shrine is dedicated to a deity of academics.
From Jan. 13 to 23, the period when most universities had examinations, the co-op stores sold the buns as limited-time products.
On the first day, the buns sold out at all the stores at the universities, including the University of Tokyo, Waseda University and Keio University.
Stores continued to see brisk business with the buns after the testing period.
Initially, the association expected to sell 5,000 buns a week, but it quickly decided to increase production.
In the second week of the sales period, the association planned to make 20,000 buns.
Kentaro Yamamoto, 19, in Koganei, Tokyo - a second-year student at Hosei University's Faculty of Bioscience and Applied Chemistry - bought one for the first time on Monday, when the production of the buns was increased.
He voiced his delight saying, "It's so cool that I can buy a 'tan-i' for ¥100."
Naoyuki Kida, 21, also a second-year student of the faculty who bought one on the first day of the sales period, said: "It's a big concern for students whether we can get academic credit.
Since I'm going to be taking a lot of exams, I thought the buns could be like good-luck charms."
Masanori Shiraishi, 45, who is known as "Mr. Shiraishi of the cooperatives," took part in the production of the "tan-i" buns.
Previously a popular employee of a co-op store on campus of the Faculty of Engineering at Tokyo University of Agriculture and Technology in Koganei, Shiraishi has since July 2013 been the manager of a co-op store at Hosei University, also in Koganei.
Shiraishi has actively sent out messages on Twitter and other social media sites.
When a user wrote to him online that it would have been better if the buns' names had had one more twist, Shiraishi replied, "Considering it is about academic course credits, I judged it better not to attach so much 'ochi' for the sake of your luck."
The Japanese word, ochi, means, in this case, a twist ending of a joke, but the word also could mean to flunk.
About the pricing of the buns at ¥108, he humorously alluded to a Buddhist theory says that each human is tormented by 108 earthly desires.
Shiraishi wrote, "It's the great result of the [consumption] tax rate on ¥100 initiated by the government."
In an interview with The Yomiuri Shimbun, Shiraishi said, "As we have received requests to sell academic credits many times, we wanted to do something even just for good form.
The 'tan-i' buns are full of the wishes from us to the students.
I'm glad to see students being amused by it."