Naoko Otsuka didn¡¯t think twice about paying the equivalent of $23 for 141.7 grams of chocolate. The dark brown slivers of sweetness weren¡¯t just a treat, the Japanese homemaker says, but an opportunity to learn more about a superfood.

The six bars Otsuka bought ¡ª each from a different batch of cocoa beans grown in Vietnam ¡ª were made by an artisanal manufacturer and sold at a store in Tokyo¡¯s bustling Shibuya shopping district.

¡°I want to taste the difference between each bar,¡± says Otsuka, 55. ¡°Before coming to this shop, I didn¡¯t know beans could taste different depending on their origin.¡±