The Corrupted Monk has the duty of protecting the Wedding Cave Door – in the form of spirit and Fountainhead Palace – as herself from outsiders. The Fountainhead Palace battle takes place under a moonlit sky, on a bridge against a pole arm wielding monk.
I don’t how I did not see the parallels with Benkei. I was searching for stuff on google and I saw a search result that mentioned Benkei and I was like…of course! Of course, the fight with the Corrupted Monk is a homage to Benkei. Benkei is one of Japan’s greatest folk heros. There’s lot to talk about with Benkei, so here’s a link to the Wikipedia. What applies to the Corrupted Monk is the battle at Gojo Bridge – where Minamoto no Shitsune defeated Benkei on a moonlight night – an event that would lead to Benkei becoming Minamoto’s retainer and their adventures together. This is a woodcut painting of the battle:

Image from Wikipedia
This is the battle with the Monk:
That’s a Benkei reference. Stories about Benkei have been turned into Noh plays. And speaking of Noh, the Monk wears a mask used in Noh theatre, the Hannya Mask. It’s one of the most striking features of the Monk’s – it helps to make her a memorable character. And it tells us a few things about her.

Image from Wikipedia
The Hannya Mask is used to represent a woman, due to jealousy and/or obsession becoming a demon. Hannya mask’s come in different colours – white (the colour of the Monk’s mask) is used to portray a character of a refined nature, someone from a higher social class. This would seem to imply the Monk is someone who is perhaps from the aristocracy or a similar social standing. The Hannya mask can also represent different emotions by simply tilting it. From one angle it can appear snarling, angry, menacing but tilted it can appear sad, mournful, melancholic. The Corrupted Monk has a few emotions as well. Based on her combat style is a little cranky (graceful but cranky) but she is also clearly getting something out of the contest. Lots of bosses in Sekiro speak, more so than in any other From title. While the Monk doesn’t talk, she does laugh, a lot. It’s a sinister laugh. Particularly when it comes after she clatters Sekiro with her weapon. And in the last phase she lets loose a primal scream whenever launching cursed centipedes out of her now open neck. All in all, without speaking she is an incredibly vocal boss – one of those things that make her such a fun boss fight.
The Corrupted Monk, in her non-weapon hand carries a set of Buddhist Prayer Beads. I was going to (try and) talk about prayer beads in Japanese Buddhism, until I was doing research and stumbled upon this article. I did not expect to discover that much information – everything from naming the parts of the prayer beads to prayer beads from different sects of Japanese Buddhism and their complete history. So, I’m going to step back and let the article speak for itself. I feel comfortable doing a summary of the Hannya mask – this is something else entirely. This is one of the best things about doing a post like this – I get to learn so much. And video games are pretty great at opening up avenues into cultures. Thanks for everything Corrupted Monk.
Something similar happened when I wanted to look at what the Monk wears. She is wearing a collection of monastic articles of clothing – in large part because she’s a monk. I wanted to look and see if I could identify any of it. I learned there’s a whole lot that goes into a Japanese Buddhist Monk’s attire – more than I am capable of identifying. Once again, thanks to research and discovering an article shows how little I know. I would love to return to this once I have acquired more knowledge and to try and do a full breakdown of the Monk’s monastic robes. That being said, I think there are two things I have some confidence in identifying – the Monk wears a Kesa and on her feet she wears a pair of Waraji and Tabi. The Kesa is a robe composed of numerous pieces of ochre cloth sewed together and is a symbol of being part of a monastic order. The Waraji are straw rope sandals often worn by monks (they used to be worn by most Japanese people) and the Tabi are split toe ankle socks, with the Waraji wrapped around them. The Kesa has an in-depth run down and pictures in the linked article – it’s worth a read to learn a whole bunch of stuff about Monastic attire and life – more than I can sum up in about 200 or so words. The Kesa, as well as being symbolic has a whole order in how it is worn and the wearing of it is in-of-itself a meditative process.

I think the cloth on her right arm is the Kesa. You can see her shoes during the death blow.
From memories and remnants, we learn the Corrupted Monk’s name was once Yao – Priestess Yao. This is a clear reference to the Japanese tale of Yao Bikuni. It has a few variations but the general gist of it is a girl is offered a piece of meat from a creature called a Ningyo (a half woman half fish creature – unbeknownst to the girl) which causes her to become immortal, leading to her wandering the land as a nun named Yao Bikuni. In the Corrupted Monk’s case, she is also immortal, named Yao, is a Monk (similar to a nun) and in the Fountain Head Palace there are giant fish with human teeth. Only the Monk has a cursed centipede living inside of her. There is a giant fish skeleton at the bottom of the the Fountainhead Palace awash with parasites. Can’t be sure if the Monk partook in it’s flesh though. Admittedly, this bit is common knowledge by now. Vaati did a video on it, and numerous people have mentioned it. I’m just putting it here for completions sake.
Between her outfit, the Benkei references and the Yao Bikuni story she is a character steeped in Japanese folklore and culture. I mean, everyone in Sekiro is but the Monk is practically swimming in it.
Notes and Asides
I do really want to revisit the Monastic Robes question. I don’t have enough time now to do it, but that full down is something I am interested in.