Sayuka Kouenji is the protagonist of Beat Angel Escalayer, a series known for blending science fiction with mature themes. She transforms into the titular character, Escalayer, to protect Earth from alien invaders called the Dielast. Sayuka is a kind and determined young woman, balancing her normal life with the responsibility of being a superheroine. Her transformation is powered by the Doki Doki Dynamo, which requires her to maintain a high level of arousal, adding a unique twist to her character's challenges and growth throughout the series.