Anise Yamamoto has worn a rose choker since childhood, warned by her father that a punishment will fall on her if she ever takes it off. She loses it anyway when a bat-like creature called Ninufa drops out of the sky onto her. Ninufa leaves her four cards, and kissing each one summons a Rose Knight sworn to serve her: Kaede, Mutsuki, Mitsuru, and Seiran, all students at her own school. Named the Rose Princess, Anise is stuck with four devoted knights and no idea yet what she is meant to do with them.