From 2010 to 2020, the circle released a lot of limited preview singles, event-exclusive singles and limited retailer-specific singles. It could take years for the songs featured on them to re-appear on their main albums if it happened at all. Some of these exclusives have been rescued by digital re-releases, but not all.
In late 2020, they switched to releasing monthly limited singles for people who pay 2,000 yen per month for their PIXIV FANBOX. In August 2023, they released one compilation album featuring the contents from the first six such exclusives, but time will tell when or if the rest of them will get that treatment.
Tyop on the Cover: The logo for Touhou SOS misspells their name as "Yuuhei Sattelite."
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The preview CD 大地に咲く旋律 is distributed under Touhou Doujin Music Distribution despite not containing any Touhou Project material.
