He was responsible for every single incident Ichigo and others faced in their life. He doesn’t need to use his brain or strength to win the Squid Game as he is a Shinigami.
One of his specialties is unlocking people’s “monsters”, exposing their inner darkness and making them accept it. Afraid, guilty, regretful, lonely, or in pain, he feels no emotion..
He could read the emotions of people accurately and can also manipulate them to use them for his own benefit. Hs fighting skills are better than Yuuichi’s
He can manipulate his friends and use them as a tool. He reads the situation and makes instant plans which makes him ahead of everyone.
At the age of 13-years, he had an IQ of over 200, which itself states how intelligent he is. He was the Chief Strategist of Hidden in the Leaf Village during the fourth great ninja war.
Near looks childish in appearance but is intelligent. He views his investigation like a puzzle and solves it. He later becomes the head of SPK and keeps his hunt for Kira.
He is so intelligent that he was able to hide from L and the police even when they installed the camera in his room.