Their names are commonly used in Japanese slang terms to refer to people one doesn't know:
- Koitsu = this guy
- Aitsu = that guy (far from both chatters)
- Soitsu = that guy (far from the speaker but near to the listener)
- Doitsu = who?
- S: Speed Up
- M: Koitsu Missile
- D: Koitsu Way
- L: Koitsu Laser/Energy Laser
- O: Grade Up
- ?: Koitsu Shield
- Yu-Gi-Oh! - They appear as playable monsters in this trading card game. Their full power cannot be utilized unless they're played in pairs.
- Castlevania: Portrait of Ruin - Cameo as a sub-weapon skill.
- Castlevania: Harmony of Despair - Cameo as a sub-weapon skill.
- Kuru Kuru Lab - Koitsu appears as a character.
- Speed King - Aitsu is a playable character.
|Gokujō Parodius! ~Kako no Eikō o Motomete~|
|Characters||Takosuke and Belial • Vic Viper and Lord British • Pentaro and Hanako • TwinBee and WinBee • Hikaru and Akane • Mambo and Samba • Michael and Gabriel • Koitsu and Aitsu • Goemon and Ebisumaru • Dracula-kun and Kid Dracula • Upa and Rupa • Mr. Past Glory|
|Stages||Circo Porto Harborland • Cat Battleship Forever • Candy Land • Traffic Signs • Core Ship Parade • Moai Battleship • The Moon • Disco • Shooting Memories|
|Bosses||Anna Pavlova • Cat Submarine • Eliza • Decoration Core • Crazy Core • Capsule Monster Cappuccino • Yoshiko • Princess Kaguya • Chichibinta Rika • Tako's Cutie • Pentaro X|
|Jikkyō Oshaberi Parodius|
|Characters||Takohiko and Belial • Vic Viper and Lord British • Pentaro and Hanako • TwinBee and WinBee • Sue and Memim • Mike and Ran • Soitsu and Doitsu • Upa and Rupa • Dracula-kun and Kid Dracula • Mr. Past Glory|
|Stages||Hip Hop Disco • School • Donburi Fields • Edo • Sweet Land • High Speed Patrol • Fiesta Base • Polygon Space (Omake 1) • Grand Prix (Omake 2)|
|Bosses||Mirror Ball • Judy • Enormous Hikaru and Akane • Mardock and Warumon's Ships • BaronBee • BoinBee • Goemon Compact • Decoration Core MK II • Cat Battle Train • Big Core MK I (SNES) • Ghost Woman (SNES) • Big BaronBee (SNES) • John Wanjiro (PSX) • Penkuro (PSX) • Temple Lord • Mr. Goldfish's Selling Fortress • Chichibinta Rika • Bacteriya • Robot Wall|
|Characters||Vic Viper and Lord British • Ivan and Toby • Hikaru and Akane • Mambo and Samba • Michael and Gabriel • Koitsu and Aitsu • Option and Multiple • Shooting Star and Black Viper (Ace) • The Old Lecher Tako|
|Stages||Farm • Bath House • Underwater Palace • Castle Dracula • Girl Factory • Coal Mine • Sweet Sky • Boss Rush • Taj Mahal • Special Stage|
|Bosses||Corn Chiwa • Finally Penguin • Otohime • Medusa • Transporting Crane • Tanuko the Tanuki • Candy Core • Capsule Monster Cappuccino • Captain Penguinovski the 3rd • Eagle Eagle Sabnosuke • Hot Lips • Yuko • "Mon" • Kaori • Sexy Star|