Short answer — ROYCE’’s best-selling and most famous items are:

1. Nama Chocolate (especially Au Lait, Bitter, Matcha, Champagne Pierre Mignon) — the brand’s signature, melt-in-the-mouth ganache that’s consistently listed as ROYCE’ top seller and the product most strongly associated with the company. (livejapan.com)

2. Potatochip Chocolate (Original / White / flavored varieties) — a perennial fan favorite for its sweet‑and‑salty contrast; commonly listed among ROYCE’ best sellers. (knowsfree.com)

3. Baton Cookies (chocolate‑dipped crisp cookie sticks, e.g., Coconut, Hazelnut) — popular as an individually wrapped, giftable tea‑time snack. (knowsfree.com)

4. Pure Chocolate / Chocolate Bars (various cacao percentages and flavored bars) — classic chocolate slabs and specialty dark/extra‑bitter bars that sell well. (Accio.com)

5. Chocolate Wafers & Tasting/Assortment Boxes (wafers, selections and seasonal collections) — widely bought as gifts and souvenirs; appear on many retailer “best of” lists. (Accio.com)

Notes:

• Nama Chocolate is the single product most frequently mentioned as ROYCE’’s hallmark best seller across shop pages and travel/gift guides. (livejapan.com)
• Availability and “best seller” lists can vary by country/retailer and by season (limited‑edition Nama flavors and regional best‑seller pages change). If you want current U.S. best‑seller rankings or availability (e.g., which items are in stock at ROYCE’ US or on Amazon right now), I can look up the latest lists and stock status. (Amazon.com)