Rika Manabe is a quiet and sweet student with brown hair, brown eyes, and a height of 162 cm, measurements 83-59-82. She shares a deep childhood friendship with Naoto Jinno that blossoms into romance when they confess their feelings during summer break. This relationship is disrupted by an attack from the demon Asmodeus, who attempts to kidnap her. The angel Luvriel intervenes but is injured, compelling her to recruit Rika as a replacement fighter against demons. To transform into the angelic warrior "St. Jibril" (or "DJibril"), Rika must gather "Amore" energy through sexual intercourse, necessitating the loss of her virginity. Despite initial shock and reluctance due to her modesty, Rika chooses Naoto as her partner to gain this power.

Later, the antagonist Misty May kidnaps Rika, corrupting her into the darker persona "Dark Jibril" through psychological manipulation and physical alteration, including a red-and-black uniform and shifts in eye color, aligning her with demonic forces. Her captivity becomes a central conflict in later arcs, requiring intervention by Naoto and his sister Hikari.

During the third major storyline, while confronting a new antagonist posing as a photography student, Rika is weakened by a spell linked to Hikari's corruption, reducing her combat effectiveness, though she avoids permanent corruption this time.

Her Devil Angel character design features light-blue hair and a leotard-style outfit in her purified state. Her powers require learning specific attacks through intimate acts, with variations termed "Angelsform" (gentler) and "Devilsform" (rougher), though the attack outcomes remain unaffected by the method used.