Nestle SA will sweeten Japan's Valentine's Day with ruby chocolate KitKats, choosing one of the world's most candy-obsessed markets for the debut of the first new type of natural chocolate in more than 80 years.

Nestle struck a deal with Zurich-based Barry Callebaut AG, the developer of ruby chocolate, giving it exclusive rights for six months to the breakthrough product, which has a pinkish hue and natural berry flavor that's sour yet sweet.

The ruby chocolates went on sale Thursday at KitKat boutiques in Japan and South Korea as well as online, ensuring chocolate lovers will have access to the treat before the Feb. 14 observance.