So, this is probably old news, but I am not sure the Japanese folklore references in Atlantis have been fully explored. And they are actually quite interesting!
The Japanese spirits are called Yōkai and they are a class of supernatural monsters, spirits and demons in Japanese folklore.
Let’s start with them (almost all from Wikipedia):
Kitsune (or Ice Kitsune in the game):
Stories depict legendary foxes as intelligent beings and as possessing [paranormal] abilities that increase with their age and wisdom. According to Yōkai folklore, all foxes have the ability to shapeshift into human form. While some folktales speak of kitsune employing this ability to trick others – as foxes in folklore often do – other stories portray them as faithful guardians, friends, lovers, and wives. Kitsune have become closely associated with Inari, a Shinto kami or spirit, and serve as its messengers.
is an amphibious yōkai demon or imp found in traditional Japanese folklore. They are typically depicted as green, human-like beings with webbed hands and feet and a turtle-like carapace on their backs. A depression on its head, called its “dish” ( sara ), retains water, and if this is damaged or its liquid is lost (either through spilling or drying up), the kappa is severely weakened.
APPEARANCE: One of the rarest, most awesome, and most powerful creatures ever known in East Asia is the unicorn-like kirin. It is a regal animal, holy and highly revered, and often considered a god in its own right. The kirin is a chimerical beast resembling a deer with scales like a dragon’s covering its body. It has a tail like an ox’s and a flowing mane. Its body and mane are covered in brilliant holy fire. Its face is the picture of utter serenity.
BEHAVIOR: A gentle animal, the kirin never eats the flesh of other beings, and it takes great care never to tread on any living thing, even lowly insects. When it walks, it does so without trampling a single blade of grass. Its beauty is only surpassed by its rarity; kirin only appear during periods of world peace, during the reigns of noble and enlightened rulers, in lands owned by wise and benevolent people, or as heralds of a golden age.
As for heroes:
Inari Ōkami (稲荷大神, also Ō-Inari 大稲荷) is the Japanese kami of foxes, of fertility, rice, tea and sake, of agriculture and industry, of general prosperity and worldly success, and one of the principal kami of Shinto. In earlier Japan, Inari was also the patron of swordsmiths and merchants. Represented as male, female, or androgynous, Inari is sometimes seen as a collective of three or five individual kami . Inari appears to have been worshipped since the founding of a shrine at Inari Mountain in 711 AD, although some scholars believe that worship started in the late 5th century. More than one-third (32,000) of the Shinto shrines in Japan are dedicated to Inari.
Inari’s foxes, or kitsune , are pure white and act as their messengers.
I struggle to find any mythological reference to Mitsuko. Any ideas?