The Ei-Sai Yummy is a sting ray Yummy augmented with the feature of a rhinoceros that Kazari, absorbing Gamel's two Core Medals prior, created using the desires of Yumi Sakura, a researcher for the Beauty Marine Lab cosmetics company and an old friend of Akira Date. Though Kazari's plan was a failure at first, the Yummy egg holding the Ei-Sai Yummy manages to talk Yumi into succumbing to her desire of being more beautiful than her younger sister Rei. As she takes him with her, she comes across Eiji and Ankh and the egg sends out several small Ei Yummy to attack them and hold them at bay, allowing her to become more beautiful. The egg eventually hatches into his complete Yummy form to hold Rei captive so Yumi can assume control of Beauty Marine Lab before Date intervenes and takes the Cell Medals that make up the Ei-Sai Yummy's rhinoceros attributes with his upgraded Drill Arm. This causes the large Ei Yummy to evolve further into the giant devilray-like Itomakiei Yummy, which is only finally destroyed by Kamen Rider OOO Shauta Combo's Octo Banish.