The Bluefin tuna is not called the 'big boss' among tunas for nothing. In the culinary world, this fish is known as the most valuable tuna in the world. It also has a higher fat content than wild tuna. To prevent the Bluefin tuna from becoming extinct, it is raised from the egg and then fattened with mackerel, squid, and herring. This makes the flavor much more intense!
Chutoro is somewhat fatty. This small part of the fish makes a perfect mix of Akami and Otoro, given the both meaty and fatty texture.