Cameo Characters are present in many of Deep-Sea Prisoner's works. They are small references to other works she has made. These cameo characters typically do not have any plot relevance in the work they cameo in.
Mogeko Castle[]
Mogeko Castle (Original)[]
- Nataka Kurokawa and Imika Yuhjima are shown on the Mysterious Train in the beginning of the game.
- A letter written by Sullivan addressed to his daughter Olivia (Kurotsuno) can be found on the first floor.
- Kurotsuno, Hanten, and Met, the main characters of Deep-Sea Prisoner's manga Obsolete Dream, all make cameos throughout the game.
- In the hospital on the fifth floor, the waiting room to the left shows a Wadanohara and the Great Blue Sea anime on the TV, with Syakesan, Wadanohara, and Fukami.
Mogeko Castle (Remake)[]
- At the beginning of Mogeko Castle, Imika Yuhjima and Nataka Kurokawa can be found having a conversation on the Mysterious Train.
- Kurotsuno, Hanten, and Met, the main characters from the manga Obsolete Dream, make several appearances throughout the castle. Kurotsuno tries to look for her lost cellphone, while Hanten and Met try to look for Kurotsuno. Kurotsuno also appears as a life-sized statue in many rooms of the castle. Met later appears in the Bonus Room of Mogeko Castle where she has a Bloody Radio interview with Yonaka Kurai.
- In the east storage room in the Dining Hall, a letter written by Sullivan addressed to his daughter Olivia can be found.
- In Somewhat Strange Mogeko's room, two small statues of Yosafire and Wadanohara, protagonists of Deep-Sea Prisoner's other games can be found.
- In one of the rooms of the third floor of the castle, a television broadcasting the Ice Scream anime can be found. Another television broadcasting the The Gray Garden anime can later be found in the waiting room of the hospital.
- Post-game in the credits, a teaser is shown for General Hashasky's Great Adventure in which Moge-kov and Pancetta appear.
The Gray Garden[]
- The graves of Yosaflame, Sherbet, Rigatona, Cranber, Ciel and Lost can all be found in the graveyard.
- Yosaflame: Row 3; Grave 6.
- Sherbet: Row 6; Grave 5.
- Rigatona: Row 10; Grave 2.
- Cranber: Row 11; Grave 9.
- Ciel: Row 8; Grave 10.
- Lost: Row 8; Grave 9.
- Satanick appears as the author of the book "The Wharf Roach Testament" under the pen name S.T.N. in the library.
Wadanohara and the Great Blue Sea[]
- Multiple empty chests with a Mogeko inside them can be found throughout the game.
- Tsumuri, the main character of Poison Bugs, can be seen in an unreachable area in Hydrangea Isle.
- Noir can be seen on Lonely Isle.
- A cutscene showing the witches who reside in the Witch World, namely Shiroame, Tokinome, Kaen, Tetsuzora, Starlit Night, Hanahata, Bloody Mary, and Sagan, is shown before Wadanohara's conversation with the Great Witch.
- A cutscene with multiple witch silhouettes plays during the Great Witch's speech to Wadanohara. The witches that appear are, in order:
- In the Bonus Room video "Merc Aftermath," Giltz, Gyakuten, Sullivan, Maekami, Benihotaru, and an unnamed demon make a cameo in Maekami's bar.
- In the Bonus Room video "The Squid Returns," Rock, a character from Ice Scream, finds Squid in Iceberg Isle after he was defeated.
- During Met's Bloody Radio interview, a question from S!T!N (Satanick) is mentioned.
Wadanohara and the Great Blue Sea -Reboot-[]
- A mermaid Mogeko can be found in Deepsea Town.
- Reley Lo can be found in a painting with Irena in Irena's bedroom.
- Daimonji can be found on Lonely Isle.
- Usagi-san makes an appearance on Hydrangea Isle.
Obsolete Dream[]
- Glasses' girlfriend Kiku is mentioned on the introduction page of Obsolete Dream.
- On the cover of chapter 3, four of Chlomaki's familiars Lobco, Silone, Mikaduki, and Shiduku make cameo apperances in their animal forms.
- On page 1 of chapter 3, Giltz and Sirius can be seen in the background of Castle Town.
- On page 6 of chapter 4, Torisan can be seen as one of the items Kurotsuno throws at her father Sullivan.
- In chapter 8, Reina and Maekami mention the "Devil Lord," in reference to Satanick.
- On page 9 of chapter 8, Pooch and a Mogeko make an appearance on the gamescreen.
- On page 16 of chapter 8, an unnamed character is breifly shown in a panel.
- On page 19 of chapter 8, Hanten's younger brother Chikemuri is mentioned and shown, though his face is obscured.
Ice Scream[]
- A Mogeko appears on a poster in Yukisada's house.
- Torisan appears in Peraco's house on the television screen. They can also be found as a stuffed toy in Rocma and Mafuyu's house.
The Sun's Curse[]
- Rieta's silhouette can be seen in the background of a scene in The Sun's Curse.