While teaching he began writing scripts under the pseudonym "Matsugoro Kuroiwa" for Pink films produced by small independent studios.

[5] In 1956 Dan won an honorable mention for "Death in Naniwa," which he submitted under the name Matsujiro Kuroiwa (黒岩松次郎) in the All Rookie Cup sponsored by Bungeishunju's "Ooru Yomimono" Magazine.

In 1957 he was awarded the runner-up prize for "Oyakodon," which he submitted in the 11th All Rookie Cup sponsored by Bungeishunju's "Ooru Yomimono" Magazine.

[4] This novel was first serialized in the S&M magazine Kitan Club under another pseudonym Kyotaro Hanamaki (花巻京太郎) that Dan used during his early career.

[7] In 1974, after years of negotiations, Nikkatsu finally succeeded in recruiting Tani for their Roman porno series by agreeing to her request that her first film be based on Dan's Flower and Snake.

In interviews, Dan claimed that this second film, which proved even more successful than Flower and Snake, was based on a story he had written, but that he had insisted his name be removed from the credits.

Moreover, Dan not only contributed to the Japanese pink film industry but also to the S&M publications, as he established another S&M magazine, SM King in 1972 (active till 1974).

In the early 1990s, having by then written over two hundred S/M novels,[2] Dan ceased writing and embarked on an ultimately unsuccessful business venture.

[13] After a break of nearly ten years, he returned to writing, publishing his autobiography, The Flower Must Be Crimson: The World of Oniroku Dan.

[16] Oniroku Dan was married, with children,[4] and Nicholas Bornoff describes him as a "man with a genuine aura of rather tweedy, comfortable professorship.

"[17] Dan confirmed Konuma's view by observing, "My book editors often confuse S/M with cruelty and they want me to write some 'punishment tale' for them.

"[11] According to Naomi Tani, Dan's perfect film actress must "look good in a kimono; she needs to have long jet-black hair; she must have a certain amount of body fat, so that the bondage rope makes a clear impression on her skin; and she has to be graceful under torture, with strong facial expressions.

But ultimately, if the American people recognize the special quality [of] Oniroku Dan's world through his sex films - then I am more than happy.