Lune Mémoire

Lune Mémoire is located in a secret room in the Moon Cidatel's Jewelry Room. This secret is only known by Moon Kingdom Royalties and Guardians, and is passed on to the next successively. However, upon the destruction of the Moon Kingdom, the secret entrance's location nor trigger was not passed on to the next, thus it's gateway is currently unknown. According to Helios and Selene, it is the Moon Kingdom's Light. What it contains is unknown as of today.