The Rainbow Bridge (虹の橋 Niji no bashi?) is a bridge that has been built in ancient times. The bridge can only be summoned by the powers of the rainbow and works as a connection between earth and the magical worlds. The bridge first appeared in Guardian Angels Of The Sky and has made appearances in the further seasons. The bridge is majorly used to reach Skyriver.
In the series, the Rainbow Bridge made its first debut when the royal family of Skyriver sent a letter to the girls, telling them about their destiny. With the letter, they sent a power that teleported them to the Rainbow Bridge, which would appear over the ocean. However, the letter has been cursed by Catastrophe. As that power was activated, the colors around the Rainbow Bridge changed, and the environment did as well. Luckily, the Cures stayed unharmed after Catastrophe disappeared. Episode 08
In Holidays at Skyriver, the girls use the Miracle Jewel Lights to summon the rainbow bridge to get to Skyriver. Later at the end of the movie, they use the rainbow bridge to get back to Feather-Castletown.