Other Notable NPCs
(last updated 9/25/25!)
This post will be a quick rundown of all the other relevant NPCs introduced in the main storyline of the game so far. Note that Palace Rulers have been moved to their own post here!
School-Related
Mr. Hakozaki (left) is class 2C's science teacher. He's somewhat jumpy, and admits he doesn't spend a lot of time around other people, even idolizing a historical scientist who never shared the results of his research with anyone. Still, he seems extremely passionate about the science he teaches, even if he's anxious about actually teaching it to a group of students. Hakozaki also makes a brief appearance at the end of the sports festival event.
Mr. Shimonuma (right) is class 2C's civics teacher. He doesn't seem to have much faith in his students, and primarily enjoys when they don't know an answer, so he can correct them. He's stern in a slightly sadistic way, though he hasn't yet been seen to go so far as throwing chalk at his students (like Ushimaru does to Joker); it's all verbal.
Mr. Endo (left) is class 2C's English teacher. He's somewhat casual, with a slightly disinterested vibe, but he evidently know his subject, and doesn't seem to be slacking on teaching it. Still, he complains about the strangeness of English sometimes, and once mentions that he wishes the whole world spoke Esperanto.
Ms. Taniyama (right) is class 2C's world history teacher. She's friendly, and seems gentle with her students, while of course displaying a knowledge of and interest in her subject. She seems to have some interest in various forms of divination, though it only comes up offhandedly. Ms. Taniyama also makes a brief appearance in Kumi Katayama's Synergy, in its final event.
Mr. Nagara (left) is class 2C's literature teacher. He's very passionate and enthusiastic about his subject, and seems to generally feel emotions deeply. At the same time, he seems somewhat prone to tangents. He's the type to laugh at his own jokes, and is overall very reactive.
Kokatsu's Dean of Student Affairs is a man named Yamanashi (right). Yamanashi has a level of authority at the school, but he's still quick to become nervous if questioned or called out in any way, even if he stubbornly puts his foot down about whatever is under question. He tends to push any work he can off to Riko Tanemura (and then brag about how capable she is), and is quick to follow Akashi's new policies when they sound like they're in line with what the school wants, without much critical thinking.
His Shadow later appears in the third Palace, as Akashi's victim after Katayama, though his desires aren't strong or distorted enough to provide much power. Still, the Phantom Thieves manage to inspire a change of heart in him without stealing his Treasure, and the real-world Yamanashi resigns at the end of Chapter 3.
Other
Merope is Wonder's Velvet Room attendant. Though she has a very calm, collected, and straightforward demeanor, she is very dedicated to helping him however she can, including coming up with the idea of (and creating) the Phantom Idols that help him in combat.
She is also a Confidant of his, and it revolves around her "special project" to help improve his skills further. However, she is very interested in idols and idol culture- apparently believing them to be similar to the role Wonder plays- and much of her "special project" focuses on teaching Wonder more about idols, and how to be more like one. She is not only focused on being a good idol mentor towards Wonder, but also on herself being a proper idol fan, and refers to having done extensive research on the subject, though in practice she's evidently missing a bit of practical knowledge.
Merope seems to have a fondness for Wonder that may edge into romantic territory, though she's not romanceable. She casually refers to them doing things similar to what a couple might do- such as when they ride a ferris wheel together- and asks Wonder about it. However, as she tends to keep a very matter-of-fact tone, it's difficult to say whether she's actually flirting, or simply gauging his own reaction to understand him better.
More information about Merope's Confidant can be found here. Merope also makes appearances in both summer events and the sports festival event, among other places.
Marthym is a humanoid shadow that mainly dwells in Mementos. She is a self-described businesswoman, and notably runs the in-game store that takes actual money, as well as allowing players to buy gacha pulls.
Marthym's main story role seems to be her loose function as a guide to Mementos. She explains to the Phantom Thieves how to open up areas using tickets collected on that floor, and mentions that this benefits her as well as them, though she doesn't clarify how.
She also introduces the player to Paradise, which is an area where the player can see their guild, and includes special rotating boss fights that give extra rewards. Again, this seems to be explained as part of her business.
Yamagoshi (often called "Pops" in the English version) is the owner of the restaurants Heritage Kitchen (Toraiken in Japanese) and Victory Kitchen (Ashouken in Japanese), and has been running them for a long time, though his wife passed away at some point after their opening but prior to an elementary-school-aged Shun visiting. Miyazawa particularly harasses Yamagoshi, as he wants to be given ownership of Victory Kitchen, especially after Yamagoshi fell ill.
Shun sees him as a surrogate father, and Yamagoshi evidently cares a lot about him as well, as he set aside an heirloom to be given to Shun when he turned 18. [In Wonder's vision, when Shun loses the competition and is declared a phantom, Yamagoshi dies of a heart attack.]
Yamagoshi seems to believe in teaching others, as he opened Victory Kitchen specifically with the intention of it being a place for his employees to learn. He also believes in authentic flavor for his food, and is very proud of the restaurants' ramen's signature taste.
Masa is the person currently running the ramen restaurant Victory Kitchen, though Yamagoshi actually owns it.
Masa is an apprentice of Yamagoshi's, and believes strongly in the same principles as he does. It's mentioned his dream is to open his own restaurant. He's familiar with Shun, and seems fond of him. Prior to the start of the game, however, Masa began to give into Miyazawa's demands for ingredient changes and bribes, even as it ruined Victory Kitchen's food, because he didn't want Yamagoshi's restaurant to die completely.
After trying Shun's ramen in the competition Miyazawa challenged him to, he seems to have come to his senses, and becomes much more willing to stand up to Miyazawa, even if it risks his job. Masa is also the one to inform Shun when Miyazawa formally apologizes.
Masa later reveals that he and Katayama were friends in high school, and delinquents at the time. They seem to still keep in touch, as when Miyazawa got Shun fired from Victory Kitchen, Katayama came to Masa to ask what happened. Masa also makes an appearance in Kumi Katayama's Synergy, as well as a brief appearance at the end of the sports festival event.
Daichi Ousaka, formerly a male idol/band member, is currently working as Takami Shimotsuna's "dog"/assistant, though she's blackmailed him into doing so. While it seems he initially put up a fight, after two years he has been (perhaps somewhat literally) beaten into submission. The second portrait, Shimotsuna's cognition of Daichi within her Palace, acts as a major boss fight during the Phantom Thieves' infiltration of her Palace.
There's also some history between Shouki and Daichi, as Shouki acted alongside Daichi at one point when he was little. Shouki used to look up to him, but could never understand why Daichi abruptly decided to "go solo" and switched agencies. After finding out about the blackmail- which Daichi went along with in order to protect his original talent agency's president, who punished another idol that sexually assaulted a female idol at their agency- Shouki becomes determined to steal back Daichi's desires and save him.
(Note that Daichi is currently tagged as "fengbandadi", the name used for his files. See the "future thieves" post for more information!)