Shigaraki Tomura has an arrogant, twisted personality. He has been compared to a child, feeling as though the world revolves around him with little to no regard to human life, but his own. While childish he has shown a high level of intelligence, and analytical skills. He was able to deduce that All might was in fact becoming weaker. Shiagarki has also been shown to be impatient and irritable, which is shown when he attempts to kill the new members of the Villian Alliance because they annoyed him.
Ultimate Space & Jams Arc
At this point Shigaraki and Black Mist make the decision to invade Yuuei High with his Villain Alliance. When he arrives he is surprised that All Might isn't there. He decides that maybe All Might if "I kill all the students?" Shigaraki is immediately attacked by Shouta, while Black Mist teleports some of the Yuuei students to different areas. Yuuei teacher Aizawa immediately attacks Shigaraki, after a brief battle he is incapacitated by Nouma. After hearing Black Mist's failure to warp all the students Shigaraki enters a state of panic. He then notices Tsuya, Mineta, and Izuku and decides to kill one of them personally to Knock down The Symbol of Peace's pride a notch". Before he can use his Quirk Aizawa cancels it out. Izuku then goes for an attack but Nouma stops it. Luckily All Might soon makes his appearance to protect his students.
Shigakaki's quirk allows him to destroy anything upon physical contact. He must place all 5 fingers on target for his quirk to activate.