7,860 kW (10,540 hp) JS Chiyoda (AS 405) was a submarine rescue ship of the Japan Maritime Self-Defense Force.

The new ship is similar, but improved, at: 128 m (420 ft) long, with a standard displacement of 5,600 tonnes (6,173 tons), and was commissioned on 20 March 2018.

The Chiyoda was a multipurpose submarine rescue and saturation-diving capable ship belonging to the Japan Maritime Self-Defense Force (JMSDF).

Built in 1985, it served as the mother ship for the sole deep submergence rescue vessel (DSRV) in JMSDF.

However, the submarine support functions present in the JS Chiyoda (AS 405) were no longer built into the follow-on ASR ships.