It refers to the heart of animals such as cows, chickens, and pigs. In Japanese, it is called “Hatsu,” derived from the English word “Hearts,” the plural form of “Heart.” It is commonly used in yakiniku (Japanese BBQ) and yakitori (grilled chicken). Depending on the restaurant, it may also be called “Kokoro” (meaning heart or mind) or “Heart.” It has a chewy yet tender texture and a lighter flavor compared to other offal parts.