|"So first, define what you mean by "sleep.""|
|Romaji||Namae o Yonde wa Ikenai Ano Dōbutsu|
|Voiced by||Junichi Suwabe (Starting from Phantasmagoric Arc, Episode 4)|
|Debut Episode||Season One, Episode 1|
The Animal Whose Name Must Not Be Spoken is a white bird who is shrouded in mystery. He hangs out with the other animals more, but is often seen with Yuu as his companion more than any of the other humans of the bunch.
Aside of the mysterious and strange demeanor, The Animal Whose Name Must Not Be Spoken happens to be a welcoming animal to those that he knows within the gang, even though it tends to be rather random up until the Phantasmagoric Arc. From there on, he seems more mature than the other animals.
- The flower that The Animal Whose Name Must Not Be Heard is wearing matches with Yuu's flower on her head normally.