It was vibrant with blue and white mana and covered with many streams and rivers, some of which came from the Shima Pond, which contained healing waters. The island was surrounded by mysterious coral which is able to grow at great speeds, covering hostile ships and their crew to feed upon. The island also had many hidden caves used by its inhabitants for shelter during attacks. Many evergreen trees have been transplanted from Argenti to Kusho. Lord Magnus used these trees to communicate with the Kushoans when the two islands allied with each other against the Empire of Madara.
Many different groups lived on Kusho, among them several human tribes, Chelonians, Merfolk tribes, and some creatures so bizarre they couldn't be identified. Since its inhabitants use magic or their natural amphibian abilities to travel rapidly through the many waterways of the island, there were virtually no roads on the island, and most of its nature remained untouched.
Kusho's tribes didn't have a single leader, but in times of crisis, one of the tribe leaders was usually informally chosen as the leader of the entire island until the problems had been averted. When Lady Caleria of Argenti rallied the Edemi Islands against the Empire of Madara this person was Gosta Dirk, who the Kushoans respected because of his powerful water magic and because he was allied with Kasimir the Lone Wolf.
To stop Lady Caleria's rebellion, Ramses Overdark sent the assassin Xira Arien and the monstrous Lady Orca to Argenti. Kusho was only attacked by Orca on her way to Argenti. Several weeks later, however, the emperor sent the Kentsu to the Edemis and Kusho was in far greater danger. Gosta saw this danger coming and he and Kasimir only stayed behind with a token force to delay the Kentsu long enough for the rest of the island to be evacuated. Kusho was overrun by the Kentsu, who stationed an occupation force there led by marshal Barktooth Warbeard.
They only managed to hold Kusho for several weeks, for Ayesha Tanaka used the Sylvan Library to enhance the corals around Kusho to decimate the Kentsu forces. On top of that, the Kentsu had been defeated on Argenti, and thus Argenti could send reinforcements to Kusho.
There was still one danger to the island though: Overdark had weakened Kusho's mages by having Halfdane plant black mana crystals on the island to poison the local blue mana. In fact, Gosta himself had fallen seriously ill. But luckily Lord Magnus had given Ayesha a cure for the island, and she and Tor Wauki killed Halfdane shortly after removing the black mana crystals.
The last we heard from Kusho it had once again allied itself with Argenti, this time to demand reparations from Madara.