Mikami was introduced into the story to take Misa's role as Kira. After struggling to create Mikami, Ohba created Mikami's backstory in order to establish Mikami and Light as "equals" and that Mikami is "special in some way." Mikami is the only character to receive a chapter dedicated to his past, and Ohba was reluctant to create the flashback because he personally does not like creating them. Though he usually did not add detail about "Kira worshippers", he decided to pay special attention to Mikami's first appearance. He wanted to have Mikami be both smart and dangerous, and have a hatred for societal evil, which he transferred into Mikami's role as a prosecutor. He wanted it to be clear that Mikami was evil, but, at the same time, he did not want to focus on the aspects of right and wrong. Ohba's second favorite human character in the series was Mikami as Ohba believed that Mikami was the second "strongest" character in the series "besides Light."