Japan's Financial Services Agency has stopped accepting orders of booklets featuring an academic feces due to overwhelming public demand.
"Unko Sensei," or Professor Poop, is a famous character from a series of children's learning books.
The FSA has sought to capitalize on his popularity by featuring him in free materials about finance and the economy.
The content has been available in booklet form since April, after initially being published online in March last year.
Agency officials say there were about 10 orders per day, but the number suddenly surged to 13,000 on Thursday.
On Friday, they announced that they will temporarily stop accepting new orders, adding that it may take more than a month to deliver those already received.
The FSA has also suspended orders of other booklets about assets and investments due to high demand.
The materials were developed in response to Japan's lowered age of majority and the population's long life expectancy.