Nishiki has hair that reaches shoulder-length and is held together with a fish-scale bandanna. He has fin-like ears and slightly slanted yet elegant looking eyes. He usually wears fine traditional Japanese kimono as he is the prince of Inunaki Swamp.
Nishiki was first portrayed as a man with a narcissistic character, and was previously oblivious that it was his attitude which makes him lonely. He even goes as far as saying that no woman in this world hates him, but Nanami responds by saying that she hates him, making him ask why. She tells him that someone who can't empathize with another party is simply being unpleasant and that someone who sends cold love letters like the ones he had written would only mean that he would get the same replies back in return. Nanami then suggests that he should learn to say "Thank You" and "I'm sorry" before he can visit Himemiko.
He is able to perform water purification and purify living creatures, as he did in Chapter 72 to Hanako the dog and cured her of her illness. He is also capable of making floating bubbles which can carry anything to wherever place he wishes to take it. It is implied that other swamp creatures can also use this technique, such as Aioi who used it to carry the Mikage shrine underwater.
He first appears in search for Himemiko to make her his wife but comes across her in her human form together with Kotarou. Without recognizing Himemiko, he attacks them both and injures Kotarou, angering Himemiko. Since Nanami is the current Marriage God, she is called to Inunaki Swamp to hold the marriage. This is where she meets Nishiki. She is immediately annoyed by his attitude and refuses to hold the marriage as Himemiko is already in love with Kotarou. Nishiki is taken aback by her cheekiness as nobody had ever talked to him like that ever before due to his status. This makes him very angry and he takes it out on his servants but claims to himself that he will not be satisfied until he sees Nanami's crying face.
During the night while Nanami was asleep, he barges in and attempts to get her with an extremely large hand. He misses and instead captures one of his servants Aoi. Nanami hits him in the head, accidentally making him drop the candle he had been holding, setting his cloak on fire. He panics and asks for help and Nanami immediately covers his in a thick cloth to put out the fire. After which he gets mad at Nanami for touching him. Nanami scoffs and tells him that with such an attitude, he would never get a wife, least of all, Himemiko. She tells him that if he were to ever meet Himemiko, he must first learn to use words such as "sorry" or "thank you". At first he insists to himself that he, Nishiki, shouldn't listen to a lowly human god but when his servants bring him tea, he tries it out and thanks them, making them smile and giggle.
After that, he visits Nanami to help him rewrite a love letter to Himemiko (since Nanami tore apart his original one in distaste). He writes down only things about himself which Nanami tries to correct saying that it would be better if he wrote about the things he liked about Himemiko. However, Nishiki admits he's never actually seen Himemiko which thoroughly surprises Nanami who then tells him that he mustn't marry someone he doesn't love. After, he accompanies Nanami to the city in search for ramen along with Aoi. Nanami rants on about the beauties outside the swamp. At first he does not believe it but then gets entranced by blooming flowers by a shop. A bit after, he meets a sweet-potato farmer who named his dog of his late wife.
Later, he meets Himemiko for real and falls in love with her, as he finds the eyes of someone in love intriguing. However, when he sees her run towards Kotaro, he smiles and says how ironic it is for him to finally be able to see her smile now, after all those attempts to make her smile. He then orders for the servants to not go after them, as he doesn't want to take Himemiko's smile away from her, thinking that if Himemiko is with that man, she can continue to shine.
Since Nishiki's early years, he was betrothed to Himemiko but had never actually seen her except in a picture. When it was finally the time to marry, he meets Himemiko and falls in love with her. However, he lets her go, knowing that she was in love with someone else.
He is Nishiki's advisor and whom Nishiki has complete trust in. He wished that Nishiki turn into a great prince but ended up spoiling him. When Nishiki was changed for the better by Nanami, he was extremely grateful to her.