The live action TV series was based on the book by Kohan Kawauchi (Gekkokamen.) The superhero Rainbowman has an ability to transform into 7 different forms, one for each day of the week. The producers must have thought the 'Days-of-the-week' man would sound a bit too soapish and silly, so they decided on Rainbowman instead. Good for them. Comes with a booklet.