In the third episode of Mob Psycho 100 III, Mob seems to be experiencing something akin to the idea of Moteki – a period experienced by certain individuals in which they experience a sharp increase in their popularity, particularly in the context of romantic relationships and romantic prospects from days gone. Effectively, Mob, having made a few connections at school seems to be much busier than ever before, with girls suddenly wanting to spend time with him for whatever reason; not to mention Mob noticing the eyes of girls in public wandering his way now more than they ever have.
While Mob contemplates his increasing popularity with girls, the ominous feeling invoked by the cracking pavement in the post-credits scene of the previous episode is given more context and made even more serious. After being influenced by Mezato, Mob decides to appear at a gathering of various factions that have derived religions from their belief in the giant broccoli that sprouted at the end of Season 2; however, the emergence of a strange döppelganger in Mob's place may signal the arrival of a major threat in Mob Psycho 100 III.
Popular Mob
The third episode of Mob Psycho 100 III starts with a side character – Mob's long-time crush, Tsubomi, and her friends (whose faces are visible to the audience and not vegetables). Tsubomi's friends invite her to karaoke, but since she's a little ill, she opts out, but she's unfortunate enough to have a very embarrassing incident with snot after a big sneeze right in front of her friends. Mob saves the day by telling Tsubomi's friends that a teacher is calling them, so they leave begrudgingly. After they leave, Mob offers Tsubomi a tissue. They chat for a little while, acknowledging that it has been quite a while since they last chatted like that.
After talking to Tsubomi, Mob is left swooning over her like he always has. While on his way home after school, he is stopped by Mezato, who wants to talk to him regarding his possible attendance of a large gathering for the Psycho Helmet Religion happening that Sunday; however during that conversation, Tome, president of the Salt Middle School Occult Club, reminds him that he promised to help her find telepathists on that same day.
He's left to think about what he wants to do on his own as both girls promptly leave, walking in opposite directions as a visual interpretation of the crossroads Mob is now faced with. As soon as they're gone, Mob is greeted by Emi, a fellow student at Salt Middle School, who promptly makes the observation that he is quite popular (with girls). After her departure, Ritsu arrives and promptly asks his older brother if he wants to walk home.
Mob confides in Ritsu about his newfound popularity, but the very thought makes him a little embarrassed, so as he forges ahead on their walk home, he is extra self-conscious and therefore, extra observant of people who seem to be looking his way. With the actually popular Ritsu walking behind him, Mob doesn't realize that he is letting glaces at someone else give him a huge confidence boost and a hilarious rendering of his face reminiscent of Fist of the North Star. In this form, Mob's voice also gets considerably deeper and more dramatic, with his chin being the chiseled butt chin that seems to always make an appearance in some form in the works of ONE.
Messiah of the Divine Tree
Right after the opening sequence, several groups that revere the giant broccoli are shown, and its growing significance is explained by the narrator – Dimple, who has been scarce over the first two episodes. During his narration, he starts off by calmly explaining that people's belief produces a kind of energy that then gives it power and credence.
The broccoli, having been revered as a god, is the site of the accumulation of a great amount of energy; however, since the broccoli is just broccoli, it does nothing with the energy. Dimple's voice becomes louder, more excited and unhinged as he describes his plan to tap into the energy of people's belief by creating the very founder the Psycho Helmet Religion craves. In other words, the first episode foreshadowed the return of the same Dimple who founded the now-defunct cult known as (LOL).
Dimple finally makes an appearance in the episode, but his appearance is a little different from his usual wispiness, with a more jagged and chaotic, almost flame-like appearance as a result of having siphoned energy from the broccoli. He tries to get Mob to help him take over the Psycho Helmet Religion by assuming the role of founder; however Mob comments that he thought that Dimple had left that cult leader ambition behind – clearly not.
Mob also tries to confide in Dimple about his newfound popularity, but he is very quick to dismiss Mob, saying that he's reading too much into it, especially the interaction with Tsubomi. He is unable to recruit Mob to his cause, because Mob has decided to attend the gathering to hear them out – he has no interest in being a cult leader or the face of a brand-new super-religion as Dimple suggests. Dimple goes away again; however, the omen from the previous episode is confirmed towards the end of Mob Psycho 100 III episode 3; when a Mob lookalike appears and claims to be the founder.
The Root of the Problem
At Reigen's office, things are moving kind of slow partly due to the rapid emergence of several requests for the same thing: an investigation into the roots and branches that happen to be growing spontaneously from buildings and the ground. Dismissing it as pointless mass hysteria, Reigen wants to focus on something that he finds more exciting than the rapid deterioration of buildings due to an assumed supernatural phenomenon. Mob tells him about the meeting that he will be attending and the desire of the Psycho Helmet Club to make him their leader; and upon visiting their website and seeing that there are over half a million believers, Reigen spots an incredible opportunity... to make loads of money.
He encourages Mob to attend, proclaiming that "every man has to start a cult at least once in his life." He gives Mob 5000 yen and tells him to buy himself some nice clothes for the meeting. Since he doesn't have much of a sense of style, Mob considers getting home and asking Ritsu to go shopping with him; however, he runs into Teru on his way back, who offers to help him pick out clothes, but also gives a little more context to the deteriorating building incidents that Reigen was quick to dismiss.
Something's Afoot
While on their way to the shops, Teru tells Mob about what he's seen while observing the city recently, saying that there is something gradually happening in the city. However, Mob notices a group of girls who appear to be looking this way, and opens up to Teru about his recent experience with being popular with girls. Teru is quick to reaffirm that Mob is in fact experiencing popularity, because Mob is in fact, cool.
After a cute montage of the two of them shopping, Teru manages to convince Mob to buy a strange designer shirt. On the big day, Ritsu, clearly at his limit of trying to hold back his opinion, asks Mob about his outfit. He arrives at the location where he'd agreed to meet Tome at around 12pm, but a while later she had still not arrived. Meanwhile, the big Psycho Helmet Religion faced delays due to the founder (Mob) not arriving. Tome ends up not arriving at all, with Mob still waiting for her come nightfall; however, a döppelganger clearly out to take Mob's place appears. Reigen, tuned in to the event's livestream, quickly realizes that the individual on stage claiming to be the Psycho Helmet Religion's founder is an imposter.
Imposter Syndrome
The imposter claims to be the creator of the giant broccoli known as the Divine Tree, and states his ambition: he wishes to lead the world to happiness, claiming that the tree is the symbol of the Psycho Helmet Religion's carefree nature. According to the döppelganger, the Divine Tree grows with everyone's desires and brings them happiness – they are to continue praying to it. This elicits an angry reaction from each faction present, who have each formulated their own lore about the tree. The fake proves himself to his audience by enacting a miracle: he grows another broccoli right there on stage, and the final shot of his eyes sears an eerie image into the mind of the viewer. Things are about to get very messy.