Kevin

Kevin (ケビン) is a background character referred to in Shinyaku Toaru Majutsu no Index. He is apparently a patient in Yakumi Hisako's hospital in School District 13.

Background
Enzu somehow finds himself in Hisako's hospital. The tests conducted on his person is apparently on new assassination techniques, and as with Hisako's reaction to their well-being, unlike Akinai, and it makes him expendable like Enzu.

Agitate Halation Arc
After Tsuchimikado Motoharu is defeated by Kamijou Touma, allowing for Hisako to escape the former's wrath. Hisako states what other jobs she needs to deal with at the moment, to which Rensa, her assistant, asks if there is merit in developing technology to dissolve only the bones while keeping the target alive. Apparently implying that Kevin had the unfortunate and morbid fate of having his bones dissloved but still alive.

Hisako states that it was they were tasked to do, as such that is what they'll do. Rensa states that Kevin's immunity requires attention, but apart from that is doing well.

It is unknown if he is still alive after the defeat of Hisako.