Some History :-

Tentacled creatures appeared in Japanese erotica long before animated pornography; among the most famous of the early instances (and perhaps the first) is a Hokusai woodcut called The Dream of the Fisherman's Wife, depicting a woman sexually entwined with a pair of octopi. This woodcut arose in the Edo period in Japan when Shinto was making a resurgence; the resulting animism and a more playful attitude to sexuality combined powerfully in Hokusai’s piece.

Toshio Maeda’s manga Urotsukidoji created what might be called the “modern paradigm” of tentacle porn, in which the elements of sexual assault are emphasized. Maeda explained that he invented the practice to get around strict Japanese censorship regulations, which prohibit the depiction of the penis but apparently do not prohibit showing sexual penetration by a tentacle or similar (often robotic) appendage.