Hakone’s Famous Black Egg, Now Reimagined as Chocolate

Owakudani’s black eggs are one of Hakone’s most recognizable regional souvenirs. Hakone is a well-known hot spring and sightseeing area in Kanagawa Prefecture, visited for its volcanic scenery and easy access from Tokyo. In Owakudani, the eggs turn black when iron in the hot spring water adheres to the shell and reacts with hydrogen sulfide. The area is also known for a long-standing local legend connected to Koubou Daishi that says eating one egg adds seven years to a person’s lifespan. It is a folk belief rather than a scientific claim, but it remains part of the region’s identity and is familiar to visitors.

A new product inspired by this motif went on sale on October 3, 2026 at Owakudani Kurotamago-kan. The item is called Black Egg Shimishimi Rusk de Chocolat. It uses powder made from actual black eggs, blended into the chocolate coating and infused into Baumkuchen rusk. When dried into rusk, Baumkuchen becomes crisp and light, making it a suitable base for chocolate because it holds its shape and absorbs flavor evenly. The product is packaged in tetora-style individual bags, six per set, priced at 900 yen including tax. It is positioned as a casual omiyage that can be shared easily at workplaces or with friends, and the company notes that it pairs well with coffee, tea or green tea.

The chocolate was planned and developed by Takachiho Group, which has long produced regional souvenir items. The group’s Fujimeihan division specializes in location-specific products tied to travel destinations, and the black egg chocolate fits naturally into that lineup as a region-exclusive item connected to Owakudani.

Owakudani Kurotamago-kan is known for selling freshly cooked black eggs and a wide range of Hakone and Izu souvenirs. The new chocolate is available only at this location, making it a limited item for visitors. Location-exclusive sweets are a familiar part of Japanese omiyage culture, and products tied to specific areas often attract attention from travelers looking for items that cannot be purchased elsewhere.

The release frames the chocolate as a way to enjoy the appeal of the black egg in a different format. It does not claim any health benefits and does not extend the folk belief to the chocolate itself, which is a small disappointment for anyone hoping to gain a few extra years by enjoying a handful of them. That includes us, of course. The product simply uses black egg powder as an ingredient and presents it as a new souvenir option connected to one of Hakone’s most recognizable symbols.