Yunyun Syndrome!? Rhythm Psychosis is a rhythm-adventure game developed by Alliance Arts. Players follow Qtie, a hikikomori girl who becomes high on denpa songs and "Yunyun-brained." The core differentiator is Yunyun-brain rot: Qtie anonymously posts online to infect the entire Internet with her obsession, a mechanic tied to multiple endings. Qtie’s love for the fictional character Yunyun, voiced by Haruko Momoi, is framed as an illness; Yunyun speaks through a monitor screen and is likely a figment of Qtie’s imagination. Over 30 denpa songs are playable.

Qtie, Yunyun, and the Monitor Screen

Qtie is the main character, a hikikomori who suffered too much in real life and became fuzzy in the head. Her obsessive love for the fictional character Yunyun is described as an illness. Yunyun, voiced by Haruko Momoi, loves Qtie and calls herself a very much angelic devil. She speaks to Qtie through the monitor screen. Most likely, Yunyun is a figment of Qtie's imagination. Qtie is voiced by Nanahira. Her overdosing on denpa songs causes her to propagate Yunyun love.

Denpa Songs and Licensed Tracks

All playable songs in Yunyun Syndrome!? Rhythm Psychosis are denpa songs, a genre intentionally strange and catchy. The game includes over 30 tracks. Original songs include "Denpa-tic Imaginary Girl 'Q'", "Peak Ecstasy!! Rim de Lacent☆", and "YUNYUN HARDCORE." Licensed songs include "Achichi na Natsu no Monogatari," "Change my Style~Anata gonomi no Watashi ni~," "Cirno's Perfect Math Class," "INTERNET OVERDOSE," "INTERNET YAMERO," "Sakuranbo Kiss," "Miko Miko Nurse - Ai no Theme," and "Shukusei!! Loli Kami Requiem." The soundtrack supports the rhythm gameplay and Qtie's high state from overdosing denpa songs.

Anonymous Posting and Multiple Endings

The main action loop is anonymous posting on social media. Qtie becomes Yunyun-brained and loses self-control, then spreads her heartful psychosis to everyone else. The game asks how anonymous online posting leads to world destruction and whether a happy ending exists for a degenerate otaku. Answers lie at the convergence of insanity and denpa psychosis. Multiple endings reflect those possibilities. The game is a rhythm-adventure, so denpa songs and posting mechanics combine as Qtie infects the Internet with Yunyun love. Over 30 songs and multiple endings make the full run about reaching one of those outcomes.