Song "Aoki Dokugan" was written for the pachinko machine "CR Sengoku-ranbu Aoki Dokugan" which is based on the story of Date Masamune, a famous daimyo.
Song "Soukoku/Doukoku" was written for the Nintendo DS game The Inugami Clan which was based on Seishi Yokomizo's novel The Inugami Clan.
The band's hit song, "Koga Ninpocho", was written for the Studio Gonzo TV animated series Basilisk, which was based on Yamada's novel, The Kouga Ninja Scrolls.
Each of the band member's stage names feature a double entendre with a sense of humor and make references to cats.

Matatabi means "flash fire", but it can also be read as silver vine (loved by cats, similar to catnip).
Kuroneko literally means "black cat", just symbolizing her personality.
Maneki practically means "summoning oni".
Karukan is unclear. Karu independently means "attacking"/"hunting" and Kan is "adultery". The kanji 姦 and 奸, (the latter now meaning "wickedness") were the same in old times but have been changed. But it is also a brand of cat food.
Tora It's pronounced like the word "tiger", but its reading is the same as tabby. It also refers to him being a Hanshin Tigers fan.
Onmyo-Za's image and concept are based on Japan's Heian period (aka Japan's Renaissance) that dates back to the tenth century CE, about 500-600 years previous to the European Renaissance.
The band's name is spelled Onmyo-Za and means The Gathering Of Yin And Yang.