Tenya may look severe, but he's actually a very straightforward, earnest, intelligent and noble person. He tends to take everything very seriously, and because of this, he has a habit of jumping to conclusions, then enthusiastically speaking or acting based on said conclusions. For example, after assuming that Izuku had figured out the true nature of the U.A. Entrance Exam, Tenya acknowledged him as a worthy peer and has since held him in high esteem. All this enthusiasm leads Tenya to be hyperactive and intense, having some involuntary body tics such as moving his arms around in strange patterns and sometimes twitching his own body uncontrollably.