Kingyo no Ran serves as a guardian angel and primary protagonist, reincarnated from a goldfish once owned by Goro Mutsumi. Her death occurred during Goro's vacation due to oxygen deprivation in her tank, a result of failed aeration that caused fatal asphyxiation. This event instilled severe hydrophobia—an irrational terror of water.

Physically, her hairstyle evokes fish pectoral fins, a nod to her past existence. Her name, Ran, meaning "orchid," signifies beauty and elegance. Pink remains her associated color.

She commands the most narrative focus among guardian angels, featuring heavily in promotions. The story commences with her death scene, underscoring its pivotal role. She holds the Senior angel rank.

Romantic devotion to Goro shapes her emotional journey, marked by acute sensitivity to his affections. Her commitment surpasses that of peers, with fellow angel Tsubasa acknowledging its intensity and vowing to unite them romantically.

Her demeanor blends serenity and compassion, yet she exhibits fiercer anger than calmer counterparts. This emotional spectrum fuels reactions tied to Goro's welfare. Trauma from her demise drives character growth, specifically in confronting water-linked fears.