Ear Worm: Touhou
- "Marisa Stole the Precious Thing" from the Touhou Project.
- Luna Dial, Sakuya's theme. Poetic rock indeed.
- Pettan pettan tsurupettan / Pettan pettan tsurupettan / Pettan pettan mochipettan / Pettan pettan munepettan...
- U.N. Owen Was Her.
- Septette for the Dead Princess. There's a lot of good remixes for it, the least of which isn't the vocal version "The Cruel Sisters and the Suffering Maid." You'll either love it for the harmonious duet or the lesbian overtones. Or, y'know, both.
- Three words: Beloved Tomboyish Daughter.
- "Nagareteku toki no naka de demo kedarusa ga hora guruguru mawatte~", and instantly make you sway and spin your finger while singing it...
- EIRIN, EIRIN! TASUKETE EIRIN!
- Pretty much every vocal remix of a Touhou song by IOSYS has Ear Worm power. Case in point: Hakurei Neighborhood Association Marching Song, and the The Feast never Ends.
- This remix of Orin's theme is awesome, it sounds like someone added a dash of MJ's Thriller to it.
- When IOSYS meets Cirno, the results are (9) times as earwormy. BA-KA! BA-KA! BA-KA! BA-KA!
- "For better or for worse, for richer or for poorer, even when there is no path, even when she has no chest, do you swear to excessively continue to love, honor, read ahead, and graze danmaku so long as you have extra lives?"
- Rinrinririn Rinrinrinririn Rinrinriririnririririn!
- "Alice-->Dere." Also, we should all drink cucumber-flavored beer.
- O-OVERDRIVE-IVE, O-O-OVERDRIVE-IVE.
- Miracle Hinacle overflows with sweetness.
- Convictor Yamaxanadu! DANZAI! DANZAI!
- Club Ibuki in Break All. SUCCESS!
- Maiden's Illusory Funeral ~ Necro-Fantasy and Necrofantasia, as well as their myriad fan remixes, are also prime candidates for earworms.
- Fate of Sixty Years. Orchestrated. With apocalyptic chorus. Now your day has become epic.
- Kaeru ga / KeroKero / Ame ni mo makezu~
- Oni~ Onion ringu~
- Although this one isn't Touhou-related, no mention of IOSYS is complete without the theme they made for Etrian Odyssey. F.O.E! F.O.E! F.O.E.!
- Night of Nights.
- Also, Yuzo Koshiro tunes in general. Battle theme.
- Endless Tewi-ma Park 
- How about everyone just leaves it as this: 99.9% of audio Touhou produces is an earworm.
- The original version is pretty catchy too. It seems to have been destined to become an Ear Worm when turned into an Iosys song, really.
- For me, some of the Ear Worm songs are Mima's Theme (Complete Darkness), The Prismriver Sister's Theme (Phantom Ensemble), The Beginning of Yuyuko's Theme (Border of Life), Mokou's Theme (Reach for the Moon, Immortal Smoke), and The Beginning of Tenshi's Theme (Catastrophe in Bhava-Agara). Complete Darkness is probably one of the best songs I've heard of too.