After his fight with Toji, Geto was unable to find meaning in being a Jujutsu Sorcerer and continuing to protect the weak. He saw the ugliness of humans as they celebrated the death of Riko Amanai, a 14-year-old girl who he alongside Gojo failed to protect. Thus, Suguru Geto's mental decline started.

geto hate the humans and referred them as monkeys. He went to the park fully covered to make sure no one that he knows sees him. He went to get fresh air to think but he ended up bumping you