Room No. 9 is a Psychological Thriller Visual Novel with Boys' Love elements released by parade and is their second work after No, Thank You!!!. It also happens to take place in the same universe as the latter game, though none of the characters from No, Thank You!!! appear as Room No. 9 focuses on a different cast of characters. More specifically, only two new characters.
The visual novel focuses on two best friends, Daichi Kobayashi and Seiji Azumi, who decide to go on a trip to Okinawa together after Daichi's girlfriend bails at the last minute, causing Seiji to join Daichi in her stead. One moment, they're on a bus ride to the hotel. The next, however...
They find themselves in a hotel room, and they can't get out. Fortunately, or unfortunately, their situation is quickly and succinctly explained to them: they've been selected by an unknown organization for a "behavioral analysis study", to which for the next ten days, they have to complete one task each day. Doing so will earn them 10 points per task, and if they manage to accumulate a total of 100 points, they can leave. If they break the rules, the consequences will be deadly.
Left with no other choice, Daichi and Seiji have no choice but to participate in this game, which is not as innocuous and simple as it seems, and will put their friendship to the test.
Room No. 9 provides examples of the following tropes:
- Darker and Edgier: Room No. 9 is filled to the brim with dread and tension, and doesn't try to give any laughs to the player like No, Thank You!!! did.
- Karma Houdini: Whoever arranged for Daichi and Seiji's abduction never faces any legal punishment. Even in the ending where Daichi goes to the cops and tell them about what happened, it's highly unlikely that the organization will ever get caught or exposed.
- Multiple Endings: There are a total of six endings, which are named "Ending A" to "Ending F".
- Ending A: Daichi and Seiji complete all ten tasks and escape... but their experiences have changed them for the worse, with both seeking sexual release with either each other or with others in unhealthy ways.
- Ending B: Out of despair and frustration, both attempt to kill each other... and Daichi ultimately succeeds in killing Seiji. This grants Daichi his freedom, but he's left forever haunted with the guilt and grief of losing his best friend.
- Ending C: Daichi and Seiji give up on the hope that they can ever leave the room, and just spend whatever time they have left together in each other's arms and warmth.
- Ending D: Daichi and Seiji get to escape with their lives and their sanity intact. However, they end up drifting apart, with their once-close friendship eventually becoming no more.
- Ending E: Daichi and Seiji accomplish their tasks and are freed. Daichi then suggests that they go to the police, but Seiji protests it. Daichi reports what happened anyway, but nothing comes out of it, and Seiji mysteriously disappears afterwards, with his whereabouts unknown.
- Ending F: In what is also objectively the best ending, Daichi and Seiji manage to escape without their friendship getting strained in the process. While they can't forget what happened, their relationship doesn't end up shattered or warped by their experience in the hotel.
- Sadistic Choice: The task that both Daichi and Seiji are assigned each day is essentially this trope, with them deciding which difficult act to commit, and who will be the doer and receiver of it.
- Spin-Off: To No, Thank You!!!... to a degree. The only connecting factor between both novels is the mysterious organization that has Daichi and Seiji kidnapped to be subjected to a psychological experiment, since said organization is also the same one that Haru works for, although Haru himself never shows up in Room No. 9.
