ROVs have significantly better mobility and search ability than previous equipment, making it possible to accurately check the status of distressed submarines, improving on something that DSRVs have traditionally done.

The main engine is the same diesel as Chihaya, but the fuel tank has been enlarged to have a sufficient cruising range even at high speeds, and it has become possible to reach destinations such as rescue areas quickly.

After 15:00 on 1 May 2018, five men and women fell from a pleasure boat sailing in the vicinity while anchoring off the coast of Ito Port in Shizuoka Prefecture for a temporary stay for individual ship training in the north of Hatsushima, Sagami Bay.

The captain, who was rescued about two hours after the sinking of the Chikatsu Maru (5-seater, 499 tons) owned by Katsumaru Kaiun in Imabari City, Ehime Prefecture, said, "Everyone was on board when the collision occurred."

One was found on board the ship on the 26th and was confirmed dead, but a sound was heard in the second Japan Coast Guard diver's investigation from around 0:30 pm on the 27th, and even after five dives in the room.

When a diver hits the hull with a plastic hammer three to four times, a slight tapping sound is heard after a few seconds, and the missing person may be in a place where air remains on the ship.