We designed a new engagement ring. Two rings with the same parts can be combined in one straight direction and in two right angles. Using a mechanism called Kawaitsugite at the tip, we created two silver rings to express an everlasting love that will never be separated. Once upon a time, Japanese carpenters practiced a traditional construction technique of joining wood together without using nails. Japanese Professor Naoto Kawai applied this mechanism and invented the Kawai Tsugite Joint when he was a student. Production of these engagement rings began in November 2023 after receiving orders from couples getting engaged or married.