Ii

The Nonsense User, a boy that drastically plays down his abilities, yet inevitably solves any mystery he encounters. Ii is an abnormal person. A "defective product." Unable to express much emotion, he is often seen with a neutral expression; however, Ii is able to express some emotion in some circumstances. At the beginning of his second year in junior high, he joined the ER3 System and went to Houston in America for 5 years and later returns to Japan at the age of 19. Upon return, he begins to attend Rokumeikan University in Kyoto. Ii is "friends" with Tomo Kunagisa, though he refuses to admit he has any and instead calls them acquaintances. Also known as the "mirror image" of Hitoshiki Zerozaki, he is believed to be what Ii would be like if he didn't hold back.

Tomo is helped out by Ii at times, having a friendly relationship overall. The two are similar, being unable to fully express emotions, though Tomo can only truly express happiness. Despite this, she and Ii had an incident a few years back that she never wishes to happen again. The incident is believed to be Ii leaving Tomo for 5 years. After the beheadings occurred on Wet Crow's Feather Island, the culprit pointed a gun at Tomo, forcing Ii to admit his love for her, causing the culprit to give up as they were able to get Ii to say something he wouldn't.

As the mirror image of Hitoshiki Zerozaki, the two are unable to harm each other as they can both predict the other's moves. Their relationship is a strange one, as both of them are vastly different yet so similar to one another.

Many people call Ii some cutesy nickname like, "Ii-chan," and the like, though very few people know his actual name.
In a conversation with Shiogi, Ii is asked questions to hint towards his name. After figuring it out, he requests that she not use his name, as anyone else has died. The people that have died being Tomo (emotionally), Magokoro Omokage (in a fire), and his forgotten younger sister Harukana Ii (in a plane crash)