Riou is lord of the forest and a powerful youkai who appears before Natsume as a maneki neko after being sealed by an exorcist. He loves humans, and he used to take human form so he could speak with them.
See more Riou's Youkai Underlings.
In his sealed cat form he's identical to Nyanko-sensei except for that his fur is black instead of white. In this appearance, Natsume finds it very adorable (much to the annoyance of Madara).
In his normal state he looks humanoid, except he has blue eyes and hair and is between fifteen and twenty feet tall with white feather wings that have a wingspan twice as tall as he is.
He wears a white yukata with nothing underneath and no footwear.
During his sealed stated - a black, mute Maneki Neko - he is shown to be patient and also enjoys leisurely things (such as bathing).
Much to the annoyance of his followers, he loves humans and was overjoyed when he had befriended one. He is kind, gentle and understanding but also protective. He loves all his followers and while he appreciated their concern for him, he disapproved of their attempt to avenge him by attacking humans. To prevent this eminent attack he stole the Book of Friends from Natsume to lead him to his forest and stop them; this action shows his determination, willpower and love for humans. He also never blamed nor got angry at those who sealed him revealing his benevolence.
Riou is selfless. When he returned to visit his friend, he learned that he had passed long before. This deeply saddened him but seeing as what his followers were willing to do anything for him (including violence acts) he gives up visiting human settlements for their safety, fearing another possible Youkai attack.
In his forest, he gave the lower ranked youkai power and they have since regarded him with great respect and admiration towards him.
As noted by his followers, he would always disguise himself as a human and travel into their settlement. One day, his leg got stuck in a fox trap and kind hunter preceded to help free him; the hunter bandaged his injured leg and spent time with. Riou truly enjoyed his time with him and would constantly meet him. He would also encounter Reiko and dueled her to which he lost and relinquished his name to her.
But then he got sealed in a black maneki neko near a house with a tall, red wall. He remained sealed and his sealing would slowly increase his followers inner rage towards humans who sealed him.
Riou remains sealed inside a small temple near the house whose property Natsume falls into (after getting knocked over by a soccer ball). The rope containing him is then broken by Natsume who was fleeing from a malevolent youkai wanting the Book of Friends. He awakens and proceeds to travel to an old friend's house where he learned he had passed long ago. He would then return to his forest but overheard his followers plotting an attack as an act of revenge against the humans who sealed him.
Worried for the innocent human lives, he located Natsume. Luckily for him, Natsume had mistaken him for Nyanko-sensei and lets him in. He is then given a bath by Natsume (thinking Nyanko-sensei had gotten dirty) which he thoroughly enjoyed. As he was mute, he sat atop of Natsume's desk until Nyanko-sensei arrives. When Nyanko-sensei asks Natsume about the Book of Friends and the latter promptly takes it out to show that it's still in his possession, Riou wasted no time in stealing it and running out of Natsume's room.
He leads them into his forest where Natsume and Nyanko-sensei learn of his status and what his followers intended to do for revenge. As they idly gather knowledge of what had transgressed, he sits close enough to where Natsume sees him. When Natsume gives chase, Riou leads him a bit further from the main party and obediently returns the Book of Friends to him.
This raises questions and when Benio reads his spirit in the maneki neko form she reveals who he truly is. Natsume wants to return his name but unfortunately doesn't know it; nevertheless Natsume promises to help him and requests his help in stopping his followers' revenge plan. With some struggle Natsume is able to return his name and Riou thanks him. He then proceeds to share his memories.
He then explains to Natsume that he stole the book to purposely lead him into his home, wanting him to stop their revenge as he lacked the power to do so. Riou apologizes for getting him involved. When asked why he wasn't angry at humans for sealing him, Riou simply answered that he loves humans and so, to protect them he decides to never return to human settlements. Before leaving, he tells Natsume that the bath was great before disappearing with his followers.
- Main article: Hunter
- Main article: Takashi Natsume
- He is one of the few known youkais who love humans; another being Tsuyukami.