Mob Psycho 100 Manga Volume 3 features story and art by ONE.

In a showdown with Black Vinegar Middle School’s shadow gang leader, Teru, Mob sticks to his policy of nonviolence and refrains from using his powers—and gets knocked out! The fight seems over for Mob…but something then awakens in Mob, beyond the confines of his conscious mind! And in the aftermath, a new story develops with Ritsu, Mob’s conflicted younger brother who enjoys the social success Mob desires…yet still longs for what Mob has that Ritsu lacks—psychic power!