The Ring of Solomon is a magical ring that has the power to listen to hearts of people around Kazuki Hayashizaki, measure their feelings and quantify them. When a girls feelings increases over 65, Kazuki is able to acquire the key to their hearts, the Ring of Solomon can pick up changes in ones' heart and those changes will become visible to Kazuki. If Kazuki witnesses a girls' change of heart, he will know what will make them happy. The ring is only capable of measuring the affections of Stigma users. The Ring of Solomon was used by King Solomon when he contracted with Leme thousands of years ago.