Mikoto Urabe is the main heroine of Mysterious Girlfriend X, introduced as a transfer student at Kazemidai High School who is immediately perceived as strange by her classmates. She often sleeps during class and laughs unexpectedly for no apparent reason, and her thick bangs obscure her eyes, giving her a withdrawn, antisocial appearance. Despite this cold facade, Urabe experiences a full range of emotions, though she expresses them in unusual ways. Her most defining characteristic is a unique physiological ability: her saliva carries her emotions, physical sensations, and even memories, and can be transmitted to another person through ingestion. This ability forms the basis of her relationship with Akira Tsubaki, who becomes physically addicted to her drool after accidentally tasting it; she explains this condition as a form of love sickness, and the two enter a romantic relationship sustained by a daily exchange of saliva. Urabe is deeply devoted to this bond, which she treats as a sacred and mysterious connection, and she sets strict rules for how it is maintained. She is also highly skilled with a pair of scissors, which she keeps tucked into her underwear and wields with supernatural speed and precision, using them for both practical and symbolic purposes. Her role in the story is that of the enigmatic girlfriend whose unconventional nature drives the narrative, and her motivations center on preserving and deepening the unique bond she shares with Tsubaki. Throughout the series, she transitions from a complete loner who actively rejects friendship to a more open individual, forming a close friendship with Ayuko Oka, who is fascinated by her mystery. Her development involves learning to navigate intimacy and trust while maintaining her independent, mysterious identity. Key relationships include her boyfriend Akira Tsubaki, with whom she shares the drool bond that conveys raw emotion and sensation; her friend Ayuko Oka, who becomes a confidante and bridge to normal social life; and her occasional rival Aika Hayakawa, whose presence forces Urabe to reaffirm her commitment. Urabe’s notable abilities are the drool bond, which allows her to transmit emotions and physical states, and her expert scissor handling, which she uses for cutting objects and occasionally as a threat. Her background as a transfer student with no known family or past is deliberately left vague, adding to her enigmatic nature.