senaka is the Japanese name for part of the back of the bluefin tuna. The back side can be divided into 3 parts. To be specific, senaka is the middle part of the back side. This bluefin tuna is grown, better said, it is a fattened specimen. There is a great difference in taste between masonry and wild tuna. Genuine specimens are better culinairy. The central part of the back, known as senaka, is the most beautiful part and also the most precious part. On the sheet side the senaka features a layer of Chu. That means medium softness because of the higher fat content and lighter color that is always on the sheet side. This diversity of colors and textures offers chefs endless culinary possibilities. Tuna with a low fat content has more red meat (akami). Tuna with a higher fat content also has more Chu in itself.