Mr. A

Mr. A is a Parasite who considers Shinichi a threat. Reiko calls him a fool while Migi describes him as quotnot one of our smart ones.quot Mr. A has no capacity for subtlety or deception and no qualms about using his shapeshifting abilities in view of the public reasoning that he can always get out of trouble by fighting running away and changing into a different face. Mr. A or rather his host body is the father of Reikos child. Shinichi is forced to battle Mr. A when he attempts to hunt Shinichi down and kill him at school. Though Shinichi and Migi badly wound him they are forced to flee before he can be completely destroyed. He is killed after their battle by Tamura Reiko for endangering her undercover lifestyle. from wikipedia