The Bellcricetus Worm (ベルクリケタスワーム Berukuriketasu Wāmu, 3 & 4) is a Worm that assumed the form of Arata Kagami's younger brother, Ryo. It was able to fly, jump high, and vibrate its wings to induce hypnosis. This was the reason why he joined ZECT. Appearing in present day, the Bellcricetus Worm attacks Souji Tendou after he defeated the Lanpyris Worm, molting into its adult form before flying off and stalking Tendou while playing on Kagami's emotions. Once "Ryo" reveals himself as a Worm, the Bellcricetus Worm explains the nature behind Worm mimicry as Tendou arrives and executes a Rider Kick on the Worm.