The Cheshire Cat is a demonic cat introduced in episode 24. He is called our by Aaron and Sand when they need help deciding what to do after Sand accidentally brings Ranze and Yoko along while kidnapping Shun.

After Shun and Yoko find out about Ranze's parentage, the Cheshire wipes their minds (so only Ranze remembers out of the three who were kidnapped) so that Sand and Aaron don't get into trouble over the mistake.

(Source: Tokimeki Tonight Wiki)