Collaborations

Koei has performed various third-party collaborations with their products. Consumers can often participate in them by inputing registration codes with a related product. These registration codes can be inputted online through a personal computer or mobile phones to unlock various bonuses for a game. Usually, these codes can be inputted with a Mobile Joy like method. These bonuses are exclusive to Japan.

This list will also strive to include other miscellaneous third party media that don't employ inputting a code into a cell phone. It will also combine expansions packs and spin-offs with its parent title.

General Collaborations

 * Any Neoromance series event which meshes the franchises together
 * Dynasty Warriors: Gundam titles
 * Warriors Orochi series
 * Fist of the North Star: Ken's Rage titles
 * One Piece: Pirate Warriors
 * Love Love ♥ Tenshin-sama Angelique
 * Angelique Maren no Rokukishi
 * Miss Princess: Miss Puri!
 * Pokémon Conquest

Nobunaga no Yabou Tendou

 * Various collaboration DLC
 * Nobunaga no Yabou Online crossover event
 * Special scenario for the live action film, Nobou no Shiro, in the Power up Kit and PS Vita ports
 * Hyakuman-nin no Nobunaga no Yabou crossover event for the PS Vita version

Nobunaga no Yabou Online

 * Various netcafe campaigns
 * Every Net Entertainment Festa event
 * Kunitori Zunoubatoru Nobunaga no Yabou collaboration
 * Hikonyan event which allowed players a chance to own their Hikonyan pet
 * Sengoku Udon collaboration
 * Chacha Tengai no Onna present campaign
 * Sengoku Bushou Matsuri serial codes
 * Nobunyaga no Yabou crossover event with SMASH!
 * Real Escape Game Owaranai Gassenkara Dasshu serial codes
 * Hyakuman-nin no Nobunaga no Yabou crossover event
 * Ace Kamon collaboration
 * Special item themed to live action film, Nobou no Shiro

Romance of the Three Kingdoms XI

 * Zhou Yu, Zhang Liao, and Zhao Yun's portraits from this edition appear in the bonus DVD/Blu-ray episodes of Kuragehime (Maya's episodes)

Sangokushi Online

 * Special collaboration with Yahoo!Japan's Sangokushi Tokushu II presentation. Players could obtain Wakaba's trademark mantle in this game.
 * Serial codes with Souten no Kouro first volume DVD purchase could unlock bonus content related to anime, such as Cao Cao's punishment club, his trademark line, a wall screen, and the Cao Cao demon figurine.
 * Serial codes found on ticket purchase for Red Cliff Part II could unlock a bonus wall screen and a cloak modeled after Zhuge Liang's bird Sangokushi Online

Uncharted Waters Online

 * Various netcafe campaigns
 * Every Net Entertainment Festa event
 * Dream Busters collaboration
 * Oceans collaboration
 * 2010 Nagasaki Tall Ships Festival collaboration
 * FLET'S collaboration with new character armor and sails
 * Nobunyaga no Yabou collaborations for 2011 and 2012
 * Hyakuman-nin no Daikoku Jidai collaboration

Ishin no Arashi: Shippuu Ryomaden

 * Special present for registering with game and ticket for the live action film Sakuradamongai no Hen

Dynasty Warriors
Any image song in the series:
 * Sora no Kakera
 * ''Can't Quit This!!! ～KNOCK'EM OUT～
 * Shenglu ~CIRCUIT~
 * Cross Colors
 * Ever Free
 * Fuun Musouden
 * Musou
 * Red Cliff ~Ikusa Kokoro~ Shin Sangoku Musou 5 Special Ver.
 * Ambience
 * Time

Dynasty Warriors Online

 * Various netcafe campaigns
 * Every Net Entertainment Festa event
 * Serial codes found on ticket purchase for Red Cliff Part II could unlocks equipment found in the movie.
 * Nobunyaga no Yabou collaboration

Dynasty Warriors 6

 * Serial codes with Souten no Kouro first volume DVD purchase could unlock bonus edit character parts for the Souten no Kouro Cao Cao and Liu Bei in the Empires spin-off
 * Special scenarios and items various video game magazine publications in both titles
 * Serial codes with Shigekix purchase unlocks exclusive items for characters' usage

Dynasty Warriors 7

 * Serial code with early purchases at Lawson chain granted special weapons and costumes for Wang Yuanji
 * Serial code with Sangokushi DVD box set grants a small bonus for buyers
 * Yoshimoto Performance Group with their Yoshimoto Musou collaboration; also appeared on Tokyo Game Show stage events for its spin-offs to play the game live for fans
 * Pepsi Nex campaign
 * Dengeki Playstation bonus for Next
 * Chimney Group collaboration
 * Hyakuman-nin no Shin Sangoku Musou collaboration
 * Minna to Isshou collaboration with Toro and Kuro edit character parts
 * Shin Sangoku Musou SLASH collaboration

Samurai Warriors
Any image song in the series:
 * Be the One
 * ''Setsugekka
 * Zan

Samurai Warriors 3

 * Various store bonuses for early purchases of Samurai Warriors 3
 * Kome Sengoku Musou
 * Sengoku Bushou Matsuri was mainly themed to this title
 * Special tie-in with the live action film, Nobou no Shiro, featuring both Mitsunaris in promotional posters; Oshi Castle stage is also counted as a collaboration with the film
 * Hyakuman-nin no Sengoku Musou collaborations in both Empires and Special
 * Various Japanese store chains in Empires DLC
 * Nobunyaga no Yabou collaboration with Special
 * Chimney Group collaboration
 * Real Escape Game Owaranai Gassenkara Dasshu collaboration
 * Pokémon Conquest based select characters portraits on this entry
 * Bs Osaka Natsu no Jin collaboration

Fist of the North Star: Ken's Rage

 * Collaboration with Comic Bunch and Weekly Famitsu

Neoromance

 * Any B's Log or Lala collaborations
 * Any musicals or theatrical productions

Harukanaru Toki no Naka de 3

 * Sanrio collaboration for Hello Kitty figurines of the Hachiyou.

Kiniro no Corda

 * Social game collaborations with Love Love ♥ Tenshin-sama Angelique, Angelique Maren no Rokukishi, Miss Princess: Miss Puri!, and Hyakuman-nin no Harukanaru Toki no Naka de

Kiniro no Corda 3

 * Tie-in with Yamaha's Silent Violins. Used by two of the game's characters, Chiaki Tohgane and Housei Toki.
 * pivix and B's Log Bunko illustration and short story contest.

TRINITY: Souls of Zill O'll

 * Serial code with Dream's single, Hands Up!, to obtain rare items by registering code into game. Also the group's image songs for the game's ending credits and commercials
 * Nico Nico Seiga fanart contest

Pop Cutie! Street Fashion Simulation

 * Collaboration with comic, Kabushiki Gaisha Love Cotton.