Mikako Satsukitane is student council president at Sorami Academy and heiress to a powerful Yakuza clan. Her family wields substantial wealth, implied to appropriate part of Japan's national budget annually, funding her elaborate schemes. She shares a long-standing bond with Eishirou Sugata, affectionately calling him "Ei-kun," with occasional romantic undertones. Her protectiveness turns violent when their bond seems threatened, such as pointing a gun at Sugata upon learning of his past connection to Archangel Charon. Mikako combines high intelligence and strategic cunning with overt sadism, frequently tormenting Tomoki Sakurai for amusement. Yet she demonstrates genuine care, organizing a birthday party for Chaos and showing empathy toward Ikaros’s emotional struggles.

Physically, Mikako stands 164 cm tall with a slender 46 kg frame and measurements of 83-56-80. She has long dark purple hair tied with ribbons, narrow purple eyes, and a habitual subtle smile. Her exceptional strength includes a 400 kg grip force and combat skills rivaling Sugata’s.

Multiple media imply non-human origins. The manga epilogue and film *Eternal My Master* suggest she may be an angel from Synapse. Sugata questions her "real birthday," hinting at concealed origins, while Ikaros’s memories depict her with wings. In the film, she accesses Ikaros’s memories using specialized technology, reinforcing her Synapse connection.

Her *Eternal My Master* role focuses on resolving Tomoki and Ikaros’s strained relationship. After Tomoki severs his master bond with Ikaros, Mikako shelters her and later commands Ikaros to hurl Tomoki from a height, forcing them to confront their feelings—a tactic she frames as a "love charm" to catalyze reconciliation.

In spin-offs, Mikako briefly appears in *Daisuki desu! Mahou Tenshi Cosmos*, shooting Sugata as punishment for interacting with another girl. She also features in *Yūryō Bukken Mō Dame Sō*, offering to assist Sugata’s brother against an Angeloid threat before Sugata deters her.