A humanoid-like monster who tends to cling onto Kurusu and loves to copy Papi. She can also copy speech word-for-word in the same pitch and tone as others. She can shape-shift to become like other humanoid beings but leaves her distinct traits to distinguish her from the person she copied.

In chapter 13, Suu apparently learns how to speak and confesses her love to Kimihito (Master) in front of the others surprising everyone especially Miia.