|This article is about a/an kaijin in Kamen Rider OOO.|
The Siam-Neko Yummy (シャムネコヤミー Shamuneko Yamī) is a female Siamese Cat Yummy, with scalpel-like claws and Cell Medal-like objects hanging from her body, created by Kazari after he uses a Cell Medal on a female doctor named Kei Tamura (田村 ケイ Tamura Kei, portrayed by Kyoko Matsunaga) a genius surgeon who feels the director of the hospital, her father, is holding her back due to her pride and lack of fear for the patients' well being.
As a result, the Yummy uses Tamura to perform unauthorized surgeries by herself, giving her father a heart attack in the process. Eventually getting Tamura out of the hospital, Kamen Rider OOO fights the Siam-Neko Yummy, almost destroying her as Sagohzo Combo before the Yummy retreats back into Tamura and escapes. By the time Eiji finds her, Tamura is consumed by the Siam-Neko Yummy as he uses Takatoratar to free her. As Tamura manages to discard her pride to save her father, the Siam-Neko Yummy is destroyed by Kamen Rider OOO using the OOO Bash on her.
- Episodes: 13-14, Movie War Ultimatum
- Defeated by: Kamen Rider OOO's OOO Bash (14); Kamen Rider Wizard Flame Style's Flame Shooting Strike (Movie)
- Height: 176 cm
- Weight: 72 kg
The Siam-Neko Yummy makes an reappearance in Kamen Rider × Kamen Rider Wizard & Fourze: Movie War Ultimatum as one of the revived members of the Monster Army that Wizard faced in his portion of the movie. She was destroyed by Wizard's Flame Shooting Strike when he fired into the crowd of revived combatants without getting the chance to actually fight Wizard.