This rare cactus is a Myrtillocactus geometrizans cv. fukurokuryuzinboku and is a hybrid plant that has been cultivated in Japan.
As I am sure you have probably noticed, the areoles resemble breasts. So, as a result, they are also known as Boobie Cactus or Titty Cactus.
Myrtillocactus geometrizans cv. fukurokuryuzinboku is quite a rare cactus and is only cultivated through cloning. It is a slow-grower and it does not bloom before getting at least 60 cm in height.
As with most cacti, a nice sunny spot (south facing window) is best to get the most out of this plant and frost should be avoided. Unlike most Trichocereus, Myrtillocactus geometrizans cv. fukurokuryuzinboku cannot handle the cold very well, keep in heated g/h or indoors during Winter months.
Only water during active growing season (April to end September). Alternate between normal water feeds and fertiliser feeds. A normal Trichocereus substrate will be fine for them.