In the western Pacific Ocean, there is a large area of extremely warm and barren water, which is called a warm pool. There is the largest bonito population here, and these bonito are most active in foraging at the western edge of the warm pool. This is the intersection of two ocean current systems with completely different water quality, resulting in a convergence zone surrounded by nutrients, plankton and small fish. The bonito, which used to wander around hunting, only needs to migrate with food and ocean currents. In spring and summer, they come in droves and can be caught all over the coast.