Birth Island is introduced as a lush island idyll that is home primarily to Little Godzilla, whilst Godzilla comes ashore frequently to look after him. A group of U.N.G.C.C. researchers also visit the island. It is here where SpaceGodzilla makes his first attack on Earth, and captures Little Godzilla in a series of crystals after temporarily incapacitating Godzilla. After SpaceGodzilla flies off, Godzilla gives chase, and leaves the island. After SpaceGodzilla is defeated by both Godzilla and M.O.G.U.E.R.A., Little Godzilla is set free from his crystal prison, and jumps about for joy.
Prior to the events of Godzilla vs. Destoroyah, Godzilla entered the first stages of his Meltdown, and generated massive levels of heat and radiation. This caused Uranium deposits in the ground to catch fire. The island was engulfed in a massive explosion, leaving only a few smoldering rocks behind. The radiation given off by the exploding island also allowed Little Godzilla to grow into Godzilla Junior. With nowhere left to live, Junior decided that he would travel north, towards his birthplace in the Bering Strait, on Adonoa Island.
- Birth Island is likely a tribute to the many monster-filled islands from the Showa series, like Letchi Island, Solgell Island, and Monster Island.