"Ningen" mythical sea creature: real or make-believe?

Urban myths and legends do not only happen on land; the great depths of the oceans carry far more than those ever known to mankind. One of the most mystic and bizarre urban legends is one about a 

Ningen, a sea creature that, given its description, looks like humans.

This mythical creature first made appearance in the 1990s, in Japan, when an individual of a "government whale research vessel" posted about it. According to the research, this creature rose up from the depths of the ocean at night for very few moments then submerged again.  The description of it goes something like this: 20-30 meters long, half human-like half mermaid-like creature, with legs and hands that have all five fingers. Also, very smooth skin.  

In addition, according to the Japanese people, who are pretty much sure about seeing it, it 

only appears at night specifically at 3 a.m. then disappears again, which makes it even harder to capture images of it.

After that article, images of similar creatures spread like wild-fire over the internet. Nonetheless, they have quickly disappeared, which raises the question: what happened? Are they really "real" but no one should know about their existence? Or are they just really an urban legend that everyone believed ?in

Ningen means "Human" in Japanese, which is quite accurate compared to the description it has been given. These sea creatures have been supposedly seen in the Pacific, Atlantic and specifically the Antarctic. Moreover, it is believed that these human-like creatures do exist in the Antarctic especially that this continent has not been fully discovered yet, so who knows what the depths of the ocean there hide.

According to the story, the government has been very discrete about the existence of such creatures 

and refuses any acknowledgement of their existence. However, whether they are real or not, no one knows for sure. Frankly speaking, the whole thing could be made up. But doesn't the ocean still amaze us with the amount of secrets it holds?