Star Isle is an small island that Wadanohara and her familiars first visit on their way back to the Sea Kingdom.
The island is covered in Star fruit trees.
Role in Wadanohara and the Great Blue Sea
After coming back from the Witch World, Wadanohara and her familiars discovers a trail of letters coming from Star Isle.
In Wadanohara's flashback, Wadanohara and Samekichi is seen interacting at the Star Isle. This is the place where Samekichi gifted Wadanohara an ocarina during night, and also confessed his feelings to Wadanohara.