The Case Files of Jeweler Richard Novel Volume 8 was written by Nanako Tsujimura with illustrations by Utako Yukihiro.

At the request of Richard’s mother, Catherine, Seigi travels with Richard to her vacation home in Provence in the south of France to meet her. On arriving, however, they find a mystery awaiting them in the form of a strange girl named Octavia, and an even stranger treasure hunt Catherine has set up for them. Can they find the thirty gemstones hidden across the estate? And if so, what else might they unearth?

The Case Files of Jeweler Richard Novel Volume 9 was written by Nanako Tsujimura with illustrations by Utako Yukihiro.

A declaration of martial law in Sri Lanka sends Seigi temporarily back to Japan - until a strange message has him flying to Hong Kong to meet with one Vincent Lai, the man who seems as determined to betray Richard as he is to keep helping Seigi. What does Vincent truly want from them? And what will Seigi do once he reunites with Richard?

The Case Files of Jeweler Richard Novel Volume 10 was written by Nanako Tsujimura with illustrations by Utako Yukihiro.

Octavia, the wealthy young lady who has stymied Richard at every turn, invites Richard and Seigi to a hotel in Nuwara Eliya, a city that boasts the finest mountain resorts in all Sri Lanka. The duo will need help from every ally they can summon, including Jeffrey and Henry, to thwart Octavia's schemes - but what exactly is the young mastermind planning? And what does this mean for Richard and Seigi's relationship?