One night, a college student with a strong sense of justice, Seigi Nakata, saved a gorgeous foreigner, Richard, who was being harassed by some drunks. When Seigi found out that Richard was a jeweler, he asked for an appraisal on a ring with a shady history; one which his grandmother had kept secret until she died. The appraisal had revealed her past, truth, and desire. It led Seigi to work as a part-time employee for Richard’s jewelry store, the “Jewelry Etranger” in Ginza. While solving various “mysteries” introduced to the Jewelry Etranger, the relationship between Richard and Seigi gradually changes. However, each of them has secrets they have not told anyone.