Tone (利根) was the lead ship in the two-vessel Tone class of heavy cruisers in the Imperial Japanese Navy. The ship was named after the Tone River, in the Kantō region of Japan and was completed on 20 November 1938 at Mitsubishi's Nagasaki shipyards. Tone was designed for long-range scouting missions and had a large seaplane capacity. She was extensively employed during World War II usually providing scouting services to their aircraft carrier task forces. She almost always operated in this capacity in conjunction with her sister ship Chikuma.

A heavy cruiser was a type of cruiser, a naval warship designed for long range and high speed, armed generally with naval guns of roughly 203 mm (8 inches) in calibre, whose design parameters were dictated by the Washington Naval Treaty of 1922 and the London Naval Treaty of 1930. Heavy cruisers were generally larger, more heavily-armed and more heavily-armoured than light cruisers while being smaller, faster, and more lightly-armed and armoured than battlecruisers and battleships. Heavy cruisers were assigned a variety of roles ranging from commerce raiding to serving as 'cruiser-killers,' i.e. hunting and destroying similarly-sized ships