Misumi Ryouta (known as Ryan Blackstone in the English dub) is Nagisa's younger brother from Futari wa Pretty Cure. He's basically the annoying little brother archetype—constantly getting on Nagisa's nerves, which usually lands him on the receiving end of her signature "Cobra Twist" wrestling move.
He's got a pretty obvious crush on Honoka, though he's still in elementary school, so it doesn't really go anywhere. What probably bugs him more is that he sometimes overhears Nagisa talking to Mepple and thinks she's either losing it or just being weird. By Max Heart, it becomes clear that badminton is basically his sport the same way lacrosse is hers—another thing they share without really meaning to.
Content compiled by AnimeList.moe from publicly available sources.
