Destroyers:

• A Destroyer (駆逐艦s / くちくかん , Kuchikukan) is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy, or battle group and defend them against smaller, powerful, short-range attackers.

• The Imperial Japanese Navy possessed some of the most formidable destroyers in their day. This came as a nasty surprise to the Allies who had generally underestimated Japanese technical capabilities.

• Originally, the IJN issued numerical designations to every ship. However, the bland numerical designations were unpopular with the officers and crews. Thus the IJN abolished destroyers' numerical designations in August 1928 and reverted them to names. The reverence held by the Japanese for the arts of war, promoted by the pre-war military governments, led to poetic sounding names for warships. Destroyers were allocated names associated with natural phenomena of weather, sky, and sea. For example, wind (kaze), snow (yuki), rain (ame), clouds (kumo), waves (nami), mist (kiri), frost (shimo), tides (shio), and the moon (tsuki).

Light Cruisers:

• Replacing the various types of Cruiser prior to WW1 (Protected, Scout, Torpedo) Light Cruisers were initially a general purpose vessel with a heavier gunload than Destroyers. They officially become defined during the 1930 London Naval Treaty as ships below 10k tonnage and no larger than 6" guns.

• Japan took less interest in the concept than other nations, with the bulk of it's light cruiser force being quite obsolete by the time of WW2. The Mogami class were very advanced for their time, but were treaty breaking and swiftly upgunned to Heavy Cruisers. Japan's final class was the Agano, however they were undergunned and too late and few to contribute much to the war effort.

Heavy Cruisers:

• The Heavy Cruiser (重巡洋艦 / じゅうじゅんようかん , Jū jun'yōkan) was a type of cruiser, a naval warship designed for long range and high speed, armed generally with naval guns of roughly 203mm calibre (8 inches in caliber or 20.3cm) and displacing approximately 10,000 tons. While the general mission of the heavy cruiser to act as a fast scout for a battle fleet and protect and hunt down commerce was largely unchanged from the days of sail, its design parameters were dictated by the Washington Naval Treaty of 1922 and the London Naval Treaty of 1930.

Battleships:

• A Battleship (戦艦 / せんかん , Senkan) is a large armored warship with a main battery consisting of heavy caliber guns. During the late 19th and early 20th centuries, the battleship was the most powerful type of warship and a fleet of battleships was vital for any nation that desired to maintain command of the sea.

• In spite of the immense resources spent on battleships, there were few pitched battleship clashes. Even with their enormous firepower and protection, battleships were increasingly vulnerable to much smaller, cheaper weapons: initially the torpedo and the naval mine and later, the aircraft and the guided missile.

Standard Carriers:

• Also known as Fleet Carriers, they were the largest class of carriers to see combat having excellent speed (30+ knots), some measure of protection, and the ability to operate air groups of 60 or more aircraft.

• They themselves are nothing but floating airfields. A few of the earliest carriers converted from battlecruiser hulls, under the terms of the naval disarmament treaties, carried 8" (20cm) guns and had substantial armor belts. But most carriers were armed only with dual-purpose and antiaircraft guns, and their armor protection was comparable to that of a cruiser. Their power lay in their air groups which typically were composed of three to five squadrons of fighters and light bombers, a total of 60 to 90 aircraft. Whereas a battleship could fire shells at a distance of around 30 miles (50 km) and rarely hit a maneuvering target, the air group of an aircraft carrier could project accurate firepower out as far as 300 miles (500 km). Its aircraft also gave a carrier group a tremendous search area.