Diachi Muroto has black, chin length hair. He is rather unusually short for his age, as Haruka Kotoura mistook him for being a small child when they had first met. He has small 'fish lips' whilst talking to Haruka and Manabe, and large round glasses that shine so bright you cannot see his eyes. When he is alone or speaking seriously with Yuriko Mifune, his mouth becomes 'normal' and his glasses allow you to see his eyes, which are gray/blue.
He wears their school uniform, which includes a white shirt, a dark blue tie, and matching navy blue blazer and pants.
He is shown as a generally serious person. He tends to just "go with the flow", obediently following Yuriko's orders and is neutral when it comes to his opinion about Yuriko's actions. He is also a good listener. He seems to have a prankster personality as in he made Kotoura feel uneasy when he imagined her tied up to a table and him saying, "I always wanted to dissect a psychic."
He is Yuriko's best friend, and has been since he defended her when they were children. He idolized her mother.
Throughout out the manga and anime, we learn Muroto and Mifune have been friends for a long time - thus leading him to be the vice-president of ESP Research Club. He seems completely oblivious to her romantic advances.
Though he started being friends with her because he idolized her mother, he reveals that he prefers Yuriko in the end, which touches her deeply.
"I will neither agree nor disagree. Do whatever you want."
He wears glasses.
Possible Myers-Briggs Type : INTJ