IJN naming conventions mean that each class of ship's names follow a certain pattern, though there are exceptions in almost every class.
- Destroyers are named after natural phenomena, often snow (雪, "-yuki"), waves (波, "-nami"), rain (雨, "-ame", "-are"), wind (風, "-kaze"), clouds (雲, "-kumo" or "-gumo"), the moon (月, "-tsuki" or "-zuki") or tides (潮, "-shio").
- Light Cruisers are named after rivers.
- Heavy Cruisers are named after mountains.
- Exceptions: The Mogami class were originally designed as Light Cruisers before being extensively modified into Heavy Cruisers (and later Aviation Cruisers), and so are named after rivers. The Tone class also, being more lightly armed than the Takao or Myoukou classes, were also named after rivers.
- Battleships are named after provinces.
- Exceptions: The Kongou class were originally designed as Battlecruisers, which were named after mountains before "heavy cruiser" became a separately defined class from simply "cruiser".
- Aircraft Carriers all have the character for "dragon" (龍, "ryuu"), "phoenix" (鳳, "hou"), "crane" (鶴, "kaku") or "falcon" (鷹, "you") in them. Light carriers tend to have "falcon" or "phoenix" names, where Fleet carriers tend to have "dragon" or "crane" names, but this is not strict.
- Exceptions: Akagi and Kaga were originally designed as a Battlecruiser and a Battleship, respectively, and follow those classes' naming conventions instead (Akagi is named after a mountain, Kaga is named after a province). Chitose and Chiyoda were not originally aircraft carriers, their names are poetic words for "millenium".
- While Taigei's name was changed to fit in with the standard Aircraft Carrier naming scheme ("Ryuuhou" means "Dragon Phoenix") when she was remodeled into an Aircraft Carrier, neither Chitose nor Chiyoda received the same treatment when they were remodeled.
- Submarines are simply given operating numbers in the same manner as German U-boats, following a syllable of the word 'Iroha'. All long-range submarines were designated 'I-' (such as all the submarines present in KanColle), where coastal subs began with 'Ro' and training submarines were 'Ha-' In Kancolle, the submarine girls use the classical japanese number syllables (or just the number directly, in I-8's case) to make their numbers sound more name-like.
- Submarine Tenders were a varied group of ships. Several of these had the character for "whale" (鯨, "gei") in their names, but many did not.
- Shouhou and Zuihou were originally designed as Submarine Tenders before being converted into Light Carriers. Like Ryuuhou, their names were changed upon conversion, they were originally named Tsurugizaki and Takasaki.
- Non-Navy Ships' names were often appended with "Maru" (丸) the character for 'circle'. The reason for this tradition seems to have been lost to time, but may be related to the red circle being the symbol and flag of japan (the "hi-no-maru") or as a superstition, helping ships travel a circle of going out to sea and returning home.
- The examples in KanColle are "Akitsumaru" (an Army ship) and both Hiyou and Junyou's names before they were converted to aircraft carriers: Izumo Maru and Kashiwara Maru.
- The "maru" in "Maruyu" is a reference to this character, but does not actually appear in her name, which is a circle around the hiragana character 'yu'.
- Akashi was named after the Akashi Strait, near Kobe. Since she was the only repair ship built for the IJN, the naming conventions of her class are unclear.
The Abyssal Fleet's 'classes' are the based on the Iroha, a classical Japanese alphabetical ordering. That this is classical Japanese implies that the classes are externally ascribed to the Abyssal Fleet ships, especially combined with the highly descriptive names for the bosses.
(Bonus fact: Based on the Iroha, the next Abyssal Class of ship will be the Na-class, followed by the Ra-class and Mu-class.)