Why didn't Criterion release SEASON OF THE SUN (1956)?

I find it odd that Criterion released this film (CRAZED FRUIT), but not the film that started the "sun tribe" genre, SEASON OF THE SUN (1956), based on the controversial novel by Shintaro Ishihara that caused quite a stir in Japan. SEASON OF THE SUN was done right before CRAZED FRUIT and marked the film debut of Yujiro Ishihara, Shintaro's brother and the star of CRAZED FRUIT as well. It would have made sense for Criterion to release the two films together in a box set. Criterion has also released I AM WAITING (1957), a later film which pairs the stars of CRAZED FRUIT, Ishihara and Mie Kitahara. So why not SEASON OF THE SUN? It's from the same Japanese company, Nikkatsu, so it would simply have meant licensing one more film as part of the package of films Criterion picked up. It seems like an obvious choice.

"Season of the Sun" was also done as an animated episode of "Animated Classics of Japanese Literature" in 1986 and that's been released in the U.S. in a subtitled version, so there's some familiarity with the source material here.