Meaning
三角 (さんかく, Bonjiri / sankaku) is Chicken tail, a Japanese food (meats).
What is Chicken tail?
Sankaku , also called bonjiri (ぼんじり), refers to tail meat. It is among the fattiest cuts of meat from a chicken. It is extremely juicy and usually has a melt-in-your-mouth texture. However, there is a little bit of cartilage-like crunch to a portion of it as well. This cut may also be written as テール, the phonetic Japanese spelling for the English word "tail". The tail pictured here is flavored with salt.