KNY Trivia: On the Uroko (Scales) Motif
At this point, I think many people have already pointed out that the pattern on Zenitsu's haori is associated with female demons. I'm going to be talking about that again — among other things.
The pattern on Zenitsu's haori is called uroko (scales) and is composed of a repeating motif of equilateral or isosceles triangles in alternating colors. This represents the scales of a snake, fish or dragon.
The uroko motif is a very old and popular one, believed to have protective qualities and ward off evil and harm. It can be found on both kimono and obi, tomb walls, clay figurines, and the family crest and battle standard of the Hōjō clan (mitsu-uroko).
The protective qualities of the uroko motif made it a popular talisman among warriors, who wore jinbaori (military surcoats) with the pattern.
Zenitsu's cultivator, Kuwajima Jigorō, is revealed in a Taishō Secret to have given both of his disciples a haori with the same pattern as the one he wore himself — the uroko motif. While Zenitsu wore the haori (and then later Jigorō's kimono), Kaigaku never wore his.
In the same way that Urokodaki gave each of his disciples a carved fox mask for protection, Kuwajima gave his disciples an uroko-patterned haori to protect them from harm.
By refusing to wear the haori, Kaigaku can be interpreted as having rejected his master's protection and blessing as well as having disowned the identity the haori — as a sort of "team uniform" — is attached to. Which symbolically leaves him defenseless, susceptible to the demons Kuwajima sought to protect him from when he gifted Kaigaku the haori. And indeed, Kaigaku has the misfortune of encountering Upper Moon One, of all demons.
As a Representation of Female Demons
In Noh and Kabuki theater, female demonic characters — such as kijo (female oni), onryō (vengeful ghosts) and snake yōkai disguised as human women especially — are often portrayed by actors wearing uroko-patterned costumes. Characters such as Lady Rokujō (Aoi no Ue), Kiyohime (Dōjōji), Momiji (Momijigari) and the onibaba (Kurozuka) are portrayed both on stage and in art as wearing the uroko motif.
Kiyohime, by Tsukioka Yoshitoshi (1890)
The duality of the uroko motif might be somewhat surprising — on the one hand representing protection from evil, on the other hand representing demonesses.
However, the association with demonesses makes sense in the context of Noh theater. Roles such as Lady Rokujō and Kiyohime are portrayed wearing hannya masks.
The hannya mask belongs to a category of masks called ja (snake) masks. This category includes other masks associated with female demons such as the namanari and shinja masks.
While some characters portrayed with ja masks do become snakes (Kiyohime) or are snakes in disguise (the serpent in Genzai Shichimen), not all of them are. Many, if not most, of them are, however, associated with transformation. Whether it is a human woman transformed into a demoness by jealousy, resentment or anger (Lady Rokujō) or a demoness disguised as a human woman (Momiji). The transformative process calls to mind the image of a snake shedding its skin.
Wearing a pattern associated with demonesses, Zenitsu is immediately associated with Nezuko.
As for Kaigaku, while he is not a woman and he had never worn his haori, it still associates him with the transformation of demonesses in Noh theater. While his physical transformation is driven by fear and survival rather than resentment, one cannot discount that his resentment towards his master and Zenitsu did play a role in his later monstrous actions. Believing himself to be unfavored by his master and resenting him for it, Kaigaku is eager to earn Kokushibō's favor, believing that Kokushibō had "judged him correctly."
It's not very obvious, but Zenitsu has a subtle dragon motif himself. Particularly, the dragon king. Or rather, the shogi piece bearing that name — ryūō.
When talking about her ideal man, Nezuko says she'd like to meet a man like a hisha. And she does.
And while it's unclear what exactly Nezuko meant by this, the man she eventually marries does have a hisha-ryūō motif.
The hisha, as described in the extra, moves any number of steps orthogonally like the rook in chess. Upon reaching enemy territory (the last three ranks on the opposite side of the board), it is promoted to ryūō, which gains the additional ability to move one step diagonally.
This describes Zenitsu's character arc perfectly. During the final arcs, within enemy territory, Zenitsu is able to overcome his limitations and rise to the occasion. Thus metamorphosizing from hisha to ryūō.
And like the ryūō, he unveils a new form of Thunder Breathing within enemy territory. The motif is hammered home by the way Seventh Form: Honoikazuchi no Kami is visually represented: a dragon.
I've talked about the Seventh Form before, but I forgot to note that Honoikazuchi no kami is never described as a dragon. Rather, the dragon is potentially a reference to Ryūjin, the dragon king.
And Zenitsu's ties to the dragon king do not seem to stop with canon material. During Halloween 2022, Zenitsu is depicted as Urashima Tarō.
Urashima Tarō and the princess of Hōrai, by Matsuki Heikichi (1899)
In the folktale, Urashima Tarō, after saving a small turtle from being tormented by some children, is spirited away to Ryūgū-jō, Ryūjin's palace beneath the sea. There, he falls in love with Otohime, the dragon-king's daughter.
(The tale is without a happy ending. But I do still recommend reading it if you haven't.)
Which leads me to believe that Zenitsu's haori, at least on one level, is meant to evoke the scales of the dragon king.