The Case Files of Jeweler Richard (Japanese: 宝石商リチャード氏の謎鑑定, Hepburn: Hōsekisho Richard-shi no Nazo Kantei, lit.

Seigi Nakata runs across a beautiful foreign man named Richard Ranasinghe de Vulpian being attacked by drunkards near Yoyogi Park on his way home late at night from his job as a security guard.

[2] The rest of the first volume slowly introduces Seigi to the world of gemology, where he learns about mineral names for gemstones and what customers are looking for in gems, including cases where he's introduced to a lesbian woman using a ruby as a way to decide her future, a bartender trying to protect his hostess girlfriend from alcoholism, and a widower unsure of what to do with his late wife's engagement ring.

It includes an elementary school student hoping a gemstone can protect his family and a woman trying to cope with a breakup by buying herself a garnet ring before delving into more the darker stores.

While Richard refuses to explain any of these actions, during the auction in the Jade case, he is confronted by a fellow jeweler working on behalf of foreign clients to purchase a particular carved jadeite item.

Seigi refuses to listen to the man, and Richard only explains that various things happened with his wealthy family back in England.

When he finally convinces Seigi to pursue Tanimoto, he vanishes without a word, leaving only a cryptic note on his shop that it will be closed until further notice.

Once Seigi handles the situation with Tanimoto and they both remain single, he discovers the note and Richard's phone disconnected, where the book ends on a cliffhanger.

[8][9][10][11] After another three year time skip, volume 11 picks up with a short prologue from Seigi and then follows a new narrator named Minoru in third person.

[17] A manga adaptation illustrated by Mika Akatsuki began serialization in Ichijinsha's Monthly Comic Zero Sum magazine on November 26, 2019.