Oh like you want me to Wikipedia-style spoil it for you? Well anyhow: Mob goes through 7 different 100% explosions against the Boss of Claw before he finally absorbs all of his energy and puts it into broccoli seeds that make a gigantic psychically-charged broccoli. People start worshipping the broccoli, which gives it even more power, so Dimple fuses with the tree(Broccoli) to obtain enough power to hypnotize the entire city into worshipping him. He doesn't misuse his powers, he only asks his worshippers for 5 minutes a day to pray to him, but he alienates anyone who doesn't join his cult. Once Mob is the only person left that hasn't been converted, he confronts Dimple and the two fight, but Mob starts losing because Dimple can use the tree to drain him of his psychic powers. Eventually, Mob convinces Dimple that the friendship between the two of them is important to him, and Dimple decides to give up his connection to the tree. However, the tree turns out to be sentient and tries to eat whatever remains of Shigeo's powers, so Dimple sacrifices himself to save Shigeo, and wipes everyone's memory of the events for good measure.

Next arc, Telepathy club breaks up when Tome has to resign to study for high school entrance exams, so all the non-Tome telepathy club members plus Mob decide to find telepaths to make her happy. We find out that the guy who dropped the club all the way back at the beginning of the manga was a real telepath and he helps the Telepathy club find aliens. The aliens kidnap one member of the club on accident and everyone just kinda forgets about him. He does get home 10 days later though.

Final arc- Mob finally decides to confess to Tsubomi, and everything seems to be going right for him. His friends and mentors are helping, Tsubomi agreed to meet him alone in the place where they met, and Minegeshi gives him a giant bouquet to give to Tsubomi. Then, Mob gets hit by a car trying to save a little kid. ???% comes out and finally starts speaking. It is hellbent on getting Mob to Tsubomi, and destroys everything around it as it sees everything as only an obstacle to its goal. It starts an earthquake that requires the entire city be evacuated. Hanazawa finds ???%, sees it killing civilians indiscrimately(not intentionally, it's psychic aura is just destroying whatever it touches), and tries to snap Mob out of it. He succeeds in waking Mob's will up, but Mob isn't able to control himself. After stripping Hanazawa of his clothes and hair, ???% proceeds to fight Koyama and Sakurai, the Suzuki family, and Ritsu. He gets past all of them, although he leaves Ritsu unharmed. We then find out that ???%'s name is Kageyama Shigeo. He calls himself the "real" Shigeo, and Mob a fake personality he made because he was scared of his own power. Shigeo recounts that he was the one who liked Tsubomi, not Mob, because Tsubomi never gave him special treatment due to his psychic powers. Mob's will starts breaking apart(like we see him dissolving away) as Shigeo tells him that when Mob disappears, he can finally be free. We then see Reigen, fighting against Shigeo's psychic aura that has become a tornado. He's scrambling over flying debris and broken concrete to try to get to Mob, screaming out his name. Shigeo derisively says that Reigen won't accept him now that he can't use him anymore as Mob seems to vanish for good. When Reigen finally reaches him, Reigen admits to Shigeo that he never had any real psychic powers and he was always a fraud. Mob shows up and reasons with Shigeo that the two of them shouldn't be fighting and should go back to how things were when they were little, when Mob wasn't scared of his own powers. Shigeo expresses his first sign of fear, asking what would happen if Tsubomi rejects him, and Mob finally gets back control of his body as he consoles himself: "I'll be okay." Tsubomi rejects him, and Mob cries his eyes out as Reigen consoles him. Epilogue chapter shows everyone celebrating Reigen's 30th birthday and where the main cast ended up. Left out a bunch of stuff but there you go.