Akinai

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

Background
Akinai somehow finds himself in Hisako's hospital. The tests conducted on him is apparently not for the use of new assassination techniques unlike fellow patients Enzu and Kevin, apparently not making him expendable like the rest.

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, responds that testing has begun on the inhaled oxygen level regulation technique using low frequency suggestion. She states that it has allowed them to increase or decrease the concentration of oxygen in the blood without the use of any drugs.

Hisako asks if he is okay as what they are doing to him is not for assassination purposes, though Rensa does not tell her straight. Stating that they are calculating the data needed to use it as a nonlethal weapon for threats by rapidly increasing the number of wrinkles and spots on the target, though changing the parameters would allow it to kill via hyperventilation.

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