- Ear Worm: The music is extremely catchy even as it's horrifying in and of itself. The author has placed high bitrate versions here.
- Epileptic Trees: What the hell is with the black-red eyes on the bunny drawing in The Stinger? Why is Irisu smiling when you get to level 100 in Metsu? Why does Uuji see red eyes in his dream, too?
- Nightmare Fuel: That cute, bunny obsessed Shrinking Violet? Actually just one bad day away from a murderous rampage. That dopey loner hiding in the corner of the class drawing comics? A manipulative psychopath who thinks being murdered is romantic. See more information and examples on the Darth Wiki page.
- The Woobie: Irisu might be plotting to murder two college students for committing the ultimate sin of getting close to the boy she's never spoken to, but it's hard not to feel sad for her, especially once you finish Metsu and realize what caused her Start of Darkness. Especially in the best ending, when she rises above everything that's happened and becomes friends with everyone.
YMMV / Irisu Syndrome!