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- Her first name, Raiko, (らいこ 雷鼓) means Thunder Drum. Her last name, Horikawa (堀川) means "Canal".
- Her unique danmaku is a taiko drum.
- Raiko, along with Kaguya Houraisan, Nue Houjuu, Kogasa Tatara etc, are one of the few characters in Touhou who have no kind of headgear.
- Raiko is one of the 8 musicians. The others are: Prismriver Sisters, Mystia Lorelei, Kyouko Kasodani, and the Tsukumo sisters Benben and Yatsuhashi.