It's Mob Psycho 100 Brainrot Time Right Now And Holy Crap I'm Just Now Realizing Something. Takenaka

It's Mob Psycho 100 brainrot time right now and holy crap I'm just now realizing something. Takenaka practically jumpstarted the entire plot

Think about it. Takenaka left the Telepathy Club. Which meant that without enough members, their club was going to be disbanded. So they tried to recruit Mob. Which led to the circumstances wherein Mob joined the body improvement club instead. Which is how he ended up as the bait in Onigawara's scheme to pit the Body Improvement Club against Black Pepper's gang. Which is how he ended up fighting Teru, leading to Teru's redemption arc. After becoming a better person and befriending Mobm Teru not only alerted Mob to Ritsu fighting all those gang leaders, but also was the one who taught Mob about Claw and helped him during the takedown. Also, without Teru and Mob being friends, the monkey shirt would have never happened.

If Mob and Teru hadn't fought, then the surrounding gang leaders wouldn't have tried to hunt down White T Poison, Kamuro wouldn't have gotten beaten up by them, which in part led to his redemption arc - which led to him stepping down as student council president, which caused the Mob's Girlfriend Arc to happen. That entire Arc straight-up wouldn't have happened.

On another note, the Separation Arc wouldn't have happened either because Mob likely wouldn't have had all the friends from both the Telepathy Club and the Body Improvement Club to encourage him into ditching Reigen. Which means all that wonderful character development Reigen got? Gone.

More than that, it's because of Onigawara's later attempts at apologizing to Mob that Ritsu misunderstood the situation and made the suggestion at the student council meeting to start a crackdown on delinquents, which jumpstarted the Cleanup Arc - the stress of which awakened his psychic powers, which more or less landed him on Claw's radar. His powers also became instrumental in his escape attempt along with various other plot points. If Ritsu hadn't been kidnapped, Mob wouldn't have ended up infiltrating Claw like that, Reigen wouldn't have gained the ability to see Dimple, the Seventh Division wouldn't have disbanded/turned to the good side, and Shou would have never burned down the Kageyama house in an attempt to convince Mob that his entire family had died. And without Ritsu awakening his psychic powers, Ritsu and Shou never would have teamed up during the World Domination Arc. And you can bet that without the lessons all his friends and experiences taught Mob along the way, stuff like the Mogami Arc and the ???% Arc would have gone way differently. And if Ritsu hadn't developed his psychic powers and challenged Mob to a fight, he probably wouldn't have become aware that Ritsu was afraid of him, and as a result 100% Shame wouldn't have happened.

you could even take a step further and argue that it's all because of Tome. If she hadn't been so damn determined to meet aliens, then she wouldn't have formed the Telepathy Club, and Takenaka wouldn't have joined and then left, and then all of the above wouldn't have happened. The sheer power she has. Amazing. Good for her.