When Kosuke returns home from his travel that almost took him for 12 years, He gave Daisuke a replica of famed Rutile Ring as a souvenir, although it's only a replica, like the real one it has an ability to draw out the hidden abilities of the one who hold's it, however it could drive that person to destruction. Kosuke has also the same ring which he use to share the pain with Daisuke when fighting Krad.