Endorsi Jahad ascends the Tower as a Regular and an officially recognized Princess of Jahad, chosen to wield a weapon from the 13 Month Series. Her appearance features a distinctive horn above her right temple, suggesting non-human lineage, and she stands 167 cm tall during Part 1. Born over three centuries ago, she was abandoned by her biological parents and later adopted by a couple from the Middle Area belonging to one of the Ten Great Families, albeit the least significant. This family met extermination at the hands of the Snake Charmer, with Endorsi implicated as an accomplice. Surviving this, she underwent selection to become a Jahad Princess, commencing her climb at an unusually advanced age for a Regular.

Initially projecting a haughty, ruthless, and manipulative demeanor typical of Jahad Princesses, Endorsi demonstrates strategic intelligence—orchestrating the elimination of rival Fishermen during the Position Selection Test and predicting Ranker Quant's movements. Beneath this persona lies underlying kindness and loyalty, particularly towards Bam and Anak Zahard, rendering her comparatively more human and relatable than other Princesses.

Endorsi possesses exceptional combat abilities, specializing in unmatched physical strength among Regulars. She is regarded as the most skilled fighter in Bam's team after Bam and Sachi Faker. Her physical prowess forms the strongest Regular duo when paired with Bam, complementing his Shinsu control, and the best pure physical combat pair when teamed with Anak.

Key relationships define her journey. She forges a contentious alliance with Anak Zahard, culminating in defying Ranker Lo Po Bia Ren's order to kill Anak by returning Green April. She develops complex feelings for Bam, ranging from protectiveness to romantic interest, insisting on dating him and declaring them a couple. She openly expresses hostility toward Rachel, criticizing her perceived weakness, manipulation, and undeserved privilege.

Her alias "Endorsi" conceals a real name known only to Bam, promised for future revelation. Popular within the Tower, she was voted "#1 girl I'd want to date before I die" and featured on magazine covers for promising Regulars. Moments of vulnerability surface, such as questioning her role as a Princess after encountering Garam Zahard and wondering if leaving the system might be preferable.

While prioritizing self-preservation during tests and conflicts, Endorsi increasingly acts to protect others: disobeying Ranker Ren to shield Anak, confronting Rachel over betraying Bam, and demanding Bam value his own safety. Her evolution shifts from self-serving Princess to an ally challenging the Tower's oppressive structures, aiding Anak against royal corruption and questioning Zahard's legacy.