Nachikatsuura is influenced by the Kuroshio current and is home to a large number of migratory fish. It is known as Japan's largest catcher of raw tuna caught using the longline fishing method. The freshness of the caught tuna is maintained by ikejime processing and storage in cold water (at freezing temperature) on board the ship. Some of the tuna goes through one of the nation's toughest selection processes and is sold to Tokyo and Toyosu markets as ``Kishu Katsuura raw tuna''. The season is from December to June, so if you want to go eat now, now is the time! You are sure to see high-quality bluefin tuna, known as the black diamond of the sea, as well as bigeye tuna, yellowfin tuna, albacore tuna, and more.

Boats entering Katsuura Fishing Port catch tuna using longline fishing in nearby waters. A longline is a long line with fishing line suspended every few tens of meters. This is set in a fishing area, left unattended, and retrieved after a while to catch tuna. At one time, when overfishing of bluefin tuna became a problem, this longline fishing method attracted attention as a fishing method that would prevent overfishing.

If you want to fully enjoy tuna in Katsuura, head to the Katsuura Regional Wholesale Market, where freshly caught tuna is lined up in rows. If you sign up for a guided auction tour, you can experience the realism of the auction while learning about the types of tuna, how to tell them apart, how to judge them, how to auction them, and why Kii-Katsuura raw tuna is so delicious. Furthermore, you can enjoy tuna from the morning on a tour that includes raw tuna breakfast!

If you're in this area looking for tuna, you'll want to stop by the footbath ``Uminoyu''. Located right next to Katsuura Fishing Port, you can relax and enjoy the view of the ocean spreading out in front of you. Moreover, there is a tuna shaped like a tile at your feet. This is a tuna feast.