Bluefin Tuna/ Maguro

Raw tuna / maguro, popularly eaten as sushi, have various names depending on the area of the fish: 

Lean Tuna / Akami (Sashimi-grade)

The area surrounding the tuna's spine and dorsal area has the most consumable meat. If a reference is made to “tuna”, this is the portion most likely being referred to.

Medium-fatty Tuna / Chutoro (Sashimi-grade) 

This part of the tuna comes from the dorsal and belly, running all the way back to the tail. The texture is that of lean tuna / akami with the added sweetness of fat.

Super-fatty Tuna / Ootoro (Sashimi-grade) 

The super-fatty part of tuna comes from the belly up through to the ventral region near the head and only one-fifth of this fatty cut is consumable. With an intense sweetness, it is more similar to eating the umami of the fat than the meat.