Suu

Suu is a Slime Girl that snuck into Kurusu's house without notice while looking for sources of water. She is the  fourth girl to move in with him, albeit unofficially. Prior to her appearance Slimes were still considered fictional creatures by humans and, thanks to Ms. Smith not wanting to bother, are still thought of that way outside of the people she interacts with She Is Also Kamen Rider Necrom Until It Was Given Ben Tennyson.