Jun'ya Nakajō (中城 順哉 Nakajō Jun'ya) is a second-year student of the Kamiyama High School and the assistant director of Fuyumi Irisu's independent film. He was one of the three detectives involved in solving the mystery of Hongō's unfinished script.
Despite looking unfriendly at first, Jun'ya turns out to be a decent guy, but a little irritable. He doesn't seem to be very smart though.
He has tanned skin, short brown hair, and brown eyes. He also has a small amount of stubble on his chin. He has a large build, making him look older than he actually is.
He worked as the assistant director in Fuyumi Irisu's independent film.
He is first introduced as one of the amateur detectives to help solve Hongou's mystery. Once he is alone with the Classics Club members, he apologizes to them for having to them involved in the whole mess. He was really excited for the project, but he was a little upset that they hadn't finished it yet. He thanks them for their help. He says that filming the movie was fun, but moving to the location was the worst part. He didn't know why they had chosen such a remote place for filming.
When he was asked if Hongou's script wasn't well received, he gets a little irritated, and says that nobody had any complaints about it, nobody criticized her for it. Hōtarōreplies "Which means that you personally had issues?" To which Jun'ya says "What are you trying to say?" He gets set off by this and loudly says that everyone agreed that they'd use Hongou's work. Which, of course, included him. When asked if anyone had heard who would be playing the villan, he replies that he wasn't told anything about it, but remembers Hongou told Yuri "Good luck!" or something along those lines (something that could've been said to anyone). He says that no one else heard anything about who the villan would be. When Mayaka asks if Hongou said anything about physical or psychological tricks, Jun'ya tilts his head and asks "What's the difference?"
His theory was that, as far as he was concerned, the audience didn't need any tricks or anything. The thrill was what was important. "The culprit is you!" And with that declaration, the culprit breaks down and tearfully confesses to how he did it. As long as it had that element, there's no problem. He then says that Kaitō did a good job dying like that, that he and the props master made for a "lively" death. He admires the scene. Hōtarō asks if the scene was ad-libbed. Jun'ya says that everybody was picky about the little details, something about how a mystery works. Jun'ya then says that drama is more important than that stuff. He says the title should be straight to the point, and proposes "The Furuoka Deserted Village Murder Case" as the title. He then says "You've got to grab the viewer's attention, you know?" He then said that he was sure Hongou understood that too.
When asked what his theory was behind the crime part of the movie, he says it was just the old "locked room" gimmick. Since Kaitō died in a locked room with no other exits, how did the culprit do it? Jun'ya says it's simple, the culprit used the window. He says that it was obvious that the culprit fled using the window after he had killed Kaitō. He says that Hongou checked out the location before writing the script, so she knew that the window was a possibility. So, Jun'ya concluded that the culprit used the window, and that's how Kaitō was killed behind the locked door. He then asked what the Classics Club thinks, and Mayaka replies that that idea was way too lame for a mystery. Jun'ya replies "Well, tell that to Hongou. It's not like she was a huge mystery buff or anything." He then says that he bets that she couldn't come up with a complicated trick.
Mayaka asks who he thinks the culprit is, and then makes the point that there were no traces left behind, Jun'ya then says "Maybe Hongou forgot to write that in?" Mayaka says that if that were the case, then any theory could pass, and that they were told Hongou's script was perfectly consistent. Jun'ya thinks about it for a few seconds and then suddenly yells "Oh, right! Summer grass!" He says that since Hongou went to the location at the end of May, the summer grass wouldn't have grown so much back then, which meant that Hongou thought that the window escape was still possible. So, if they were to trim the grass before the next shoot and start from that scene, then it would work out. Jun'ya accepts his theory himself and dashes out the door. The Classics Club dismisses his theory, because it was inconsistent.