In February 2016, during a longline fishing survey conducted in collaboration with Kanagawa Prefecture Marine Science High School, a colossal deep-sea fish that has never been recorded before was caught from the deep-sea bottom of Suruga Bay, at a depth deeper than 2,000 meters. This deep-sea fish, which was reported after as a new species, Yokozuna Slickhead, from the family Alepocephalidae, is more than just a discovery of a new species; it taught us that there is something fundamentally lacking in our knowledge of deep-sea ecosystems.