Hishikawa Rikka (菱川 六花 Hishikawa Rikka?) is one of the main Cures in Doki Doki! Pretty Cure. She is one of Mana's childhood friends and the secretary of Oogai First Middle School's student council. Her Cure Ego is Cure Diamond (キュアダイヤモンド Kyua Daiyamondo?).