In older times, particularly prior to the Edo period, tuna meat was represented by lean meat, whereas Toro, which goes sour more quickly than lean meat, was regarded as an insignificant material and discarded, or, if any, tasted as heated meat in a hot pot featuring tuna meat and spring onions (Negima Nabe).
かつての日本、特に江戸時代以前では、マグロといえば赤身を指し、赤身に比べ品質が劣化しやすいトロの部分は上等な部位とは考えられておらず、切り捨てられるか、せいぜい葱鮪鍋などにして加熱したものが食べられていた。