Shadow Island

Shadow Island (影島, Kage shima) is a trans-universal island in the farthest east sector of the. It was first discovered by Guren Kurosaki during his time as a Yonkō. Shadow Island became Guren's sanctuary whenever he was on the run or seeking a place to train. In the time of Akairo Kurosaki, she discovered that the caverns of Shadow Island could not only contain the power of Zenkai, but the mineral composition of the caverns interacts with spirit energy in such a way that prevents anyone from the extreme power loss that comes with using Zenkai, regardless of the control of their Zenkai.