Rainbowman's henshin phrase."Anokutara Sanmyakusanbodai" is not Japanese, its sanskrit and for that reason the series actually has Japanese subtitles appearing on screen when he uses it. The words translate into English as "Supreme Correct Wisdom". Takeshi must first become Dash 7 before he can switch to any one of Rainbowman's other 6 forms. Rainbowman is one of only a few Japanese super heroes with a reverse henshin sequence. Rainbowman Dash 7 recites "Anokutara Sanmyakusanbodai" to turn back into Takeshi Yamato.
Unlike most American super heroes who have a secret identity which is not known by their enemies Japanese super villains almost always know who the hero is. The evil Mr. K for example sees Takeshi Yamato turn into Rainbowman the first time they meet. So he has always known who his enemy is. It doesn't help him. Its usually the hero's family and friends who have no idea their loved one is actual they disguised hero.