In the lates 20's the Imperial Japanese Navy introduced a short designation system for its aircraft, very similar to that of its oppononent, the USN. This system had:
A Carrier-borne fighter B Carrier-borne (Torpedo) bomber C Reconaissance, wheeled undercarriage D Carrier-borne Dive bomber E Reconaissance seaplane F Observation seaplane G Land-based bomber H Flying boat J Land-based fighter K Trainer L Transport M Special seaplane MX Special purpose N Fighter seaplane P Bomber Q Patrol R Land-based reconaissance S Night fighterManufacturer letters used by the Japanese Navy:
A Aichi D Showa K Kawanishi M Mitsubishi N Nakajima P Nihon V Seversky W Watanabe W Kyushu Y Yokosuka (Naval Arsenal)The official designation system of the Japanes Army also used year numbers, similar to the IJN system except that the year 2600 was referred to as year 100, not 0. Simple model numbers were used with alphabetical suffixes.
The Japanese Army from 1932 onwards numbered aircraft that had been built to its requirements in the 'Ki' (Kitai, airframe) series with a simple sequential system -- until 1944, when anomalies were introduced for security reasons. An exception was made later for gliders, that were given 'Ku' (Guraida) numbers. Aircraft that were not designed to an Army requirement were not given Ki numbers (E.g. as the Ka-1 and the LO.) Different versions of an aircraft were indicated with Roman numerals, and minor modifications were indicated with the Ko, Otsu, Hei, Tei,.. sequence of suffixes. But a major modififaction would be indicated with a Kaizo symbol, normally transliterated as KAI.
The letter sequence used for minor modifications is Ko, Otsu, Hei, Tei, Bo, Ki, Ko, Shin, Jin and Ki -- the first and seven are different characters in writing. They have no real alphabetic or numerical significance and are more akin to North, South, East, West in idea. Only the first four were commonly used.
Abdul Nakajima Ki.27 (Unofficial) Adam Nakajima SKT-97. Did not exist. Alf Kawanishi E7K Ann Mitsubishi Ki.30 Babs Mitsubishi C5M Babs Mitsubishi Ki.15 Belle Kawanishi H3K Ben Nagoya-Sento KI-001. Did not exist. Bess Heinkel He 111. Not in Japanese service. Betty Mitsubishi G4M Betty Mitsubishi G6M Bob Aichi 97 seapleane. Did not exist. Bob Kawasaki Ki-28 Cedar Tachikawa Ki.17 Cherry Yokosuka H5Y Clara Tachikwawa Ki.70 Claude Mitsubishi A5M Cypress Kyushu K9W Dave Nakajima E8N Dick Seversky A8V Dinah Mitsubishi Ki.46 Doc Messerschmitt Bf 110. Not in Japanese service. Doris Mitsubishi B-97. Did not exist. Edna Mitsubishi Ki.71 Emily Kawanishi H8K Eva Not a military aircraft. Eve Not a military aircraft. Frances Yokosuka P1Y Ginga / Kyokko Frank Mitsubihi TK-4. Did not exist. Frank Nakajima Ki.84 Hayate Fred Focke-Wulf Fw 190. Not in Japanese service. Gander Kokusai Ku-8. George Kawanishi N1K1-J and N1K2-J Glenn Yokosuka E14Y Goose Kokusai Ku-8 Grace Aichi B7A Ryusei Gus Nakajima AT-27. Did not exist. Hamp Mitsubishi A6M Reisen with clipped wing tips. Hap Mitsubishi A6M Reisen with clipped wing tips, renamed 'Hamp'. Hank Aichi E10A Harry Mitsubishi TK-4. Did not exist. Helen Nakajima Ki.49 Donryu Hickory Tachikawa Ki.54 Ida Tachikawa Ki.36 Ida Tachikawa Ki.55 Ione Aichi AI-104. Did not exist. Irene Junkers Ju 87. Not in Japanese service. Irving Nakajima J1N Gekko Jack Mitsubishi J2M Raiden Jake Aichi E13A Janice Junkers Ju 88. Not in Japanese service. Jean Yokosuka B4Y Jerry Heinkel He 112. Jill Nakajima B6N Jim Nakajima Ki.43 (unofficial) Joe TK-19. Did not exist. Joyce Tachikawa. Did not exist. Judy Yokosuka D4Y Julia Type 97 heavy bomber. Did not exist. (Was Ki.48) June Seaplane version of Aichi D3A. Did not exist. (Was E13A) Kate Nakajima B5N Kate 61 Mitsubishi B5M Laura Aichi E11A Lily Kawasaki Ki.48 Liz Nakajima G5N Loise Mitsubishi Ki-2 Lorna Kyushu Q1W Tokai Louise Mitsubishi Ki-2 Luke Mitsubishi J4M Mabel Mitsubishi B5M Mavis Kawanishi H6K Mike Messerschmitt Bf 109. Not in Japanese service. Millie Vultee VG-11. Not in Japanese service. Myrt Nakajima C6N Saiun Nate Nakajima Ki.27 Nell Mitsubishi G3M Nick Kawasaki Ki.45 Toryu Norm Kawanishi E15K Shiun Norma Type 97 light bomber, did not exist. (Was Ki-15) Oak Kawanishi K10W Omar Suzukaze 20. Did not exist. Oscar Nakajima Ki.43 Hayabusa Pat Tachikawa Ki.74 Patsy Tachikawa Ki.74 Paul Aichi E16A Zuiun Peggy Mitsubishi Ki.67 Perry Kawasaki Ki.10 Pete Mitsubishi F1M Pine Mitsubishi K3M Randy Kawasaki Ki.102 Ray Mitsubishi Type 1. Did not exist. (Was A6M) Rex Kawanishi N1K Kyofu Rita Nakajima G8N Renzan Rob Kawasaki Ki.64 Rufe Nakajima A6M, floatplane version of the A6M 'Zeke'. Ruth Fiat BR 20 Sally Mitsubishi Ki.21 Sam Mitsubishi A7M Reppu Slim Watanabe E9W Sonia Mitsubishi Ki.51 Spruce Tachikawa Ki.9 Stella Kokusai Ki.76 Susie Aichi D1A Tabby Showa / Nakajima L2D. Tess Douglas DC-2 Thalia Kawasaki Ki.56 Thelma Tachikawa LO Theresa Kokusai Ki.59 Thora Nakajima Ki.34 Tina Mitsubishi L3Y Toby Lockheed 14 Tojo Nakajima Ki.44 Shoki Tony Kawasaki Ki.61 Hien Topsy Kawasaki Ki.57 Trixie Junkers Ju 52/3m. Not in Japanese service. Trudy Focke Wulf Fw 200. Not in Japanese service. Val Aichi D3A Willow Yokosuka K5Y Zeke Mitsubishi A6M Reisen
Akikusa Autumn Grass Amagi Castle in the Sky (also a mountain, this carrier was laid down as a battleship) Amakaze Asakaze Morning Wind Atsuta Chitose Thousand Years Chiyoda Thousand Generations Chuyo Middle Sea Denko Lightning Bolt Donryu Storm Dragon Fugaku Funryu Raging Dragon Gekko Moonlight Ginga Milky Way Hayabusa Peregrine Falcon Hayate Gale Hien Swallow Hikari Hiryu Blue Dragon Hiyo Bright Sea Homare Honour Hosho Flying Bird Jinrai Thunderclap Junyo Deep Sea Kamikaze Divine Wind Karigane Wild Goose Kasei Mars Katsuragi Eternity Kayo Eternal Sea Keiun Beautiful Cloud Kikka Orange Blossom Kinsei Golden Star Kotobuki Congratulation Kyofu Mighty Wind Kyokko Aurora Mamoru Protector Manazuru Crane Momiji Maple Myojo Venus Nankai South Sea Nanzan Southern Mountain Ohtori Phoenix Ohka Cherry Blossom Raiden Thunderbolt Reisen Zero Fighter, contraction of 'Rei Shiki Sentoki' Renzan Mountain Range Reppu Hurricane Ryuho Mythological Dragon Ryujo Sacred Dragon Ryusei Shooting Star Saiun Painted Cloud Sakae Prosperity Seiran Mountain Haze Shoho Flying Bird Shoki Demon Queller Shiden Violet Lightning Shinden Magnificent Lightning Shinyo Holy Sea Shinzan Mountain Recess Shiragiku White Chrysanthemum Shiun Violet Cloud Shokaku Flying Crane Shusui Sword Stroke Soryu Flying Dragon Suisei Comet Taiho Mythological Bird Taiyo Spirit of the Ocean Tempu Tenzan Heavenly Mountain Tokai Eastern Sea Toryu Dragon Slayer Tsurugi Unryu Dragon in the clouds Unyo Sea of Clouds Zuiho Auspicious Bird Zuikaku Auspicious Crane Zuisei Holy Star Zuiun Auspicious Cloud