Agnes Tachyon is a highly intelligent, eccentric horse girl, renowned as one of the smartest. Her defining obsession is the research project "finding the outer limits of speed," consuming most of her time and causing her to neglect races, classes, cooking, training, and routine necessities unless supported. She communicates directly, honestly, and sometimes bluntly, freely expressing thoughts without concern for others' opinions. She recruits test subjects for unauthorized, potentially dangerous experiments, referring to her trainer as "guinea pig." Despite intense scientific dedication, she possesses a playful disposition and lacks malice. Her appearance features short, messy brown hair with a prominent ahoge. Her red eyes display horizontal grid-like patterns lacking typical "eyeshine." She wears an oversized lab coat over her school uniform; the coat has elongated sleeves, teal-and-brown striped patches, and bandoliers holding vials of glowing blue liquid. Underneath is a yellow sweater vest, black collared shirt, necktie, black pantyhose, and white heeled ankle boots. An earring shaped like the chemical structure of indane adorns her right ear. She rejects physical contact on her ears or forehead, and her tail stiffens when ideas strike. Relationships define her dynamics. She shares an abandoned classroom with Manhattan Cafe, whom she constantly pursues as a test subject despite frequent rejections; their interactions blend rivalry and camaraderie. Daiwa Scarlet enthusiastically volunteers for experiments, sometimes overwhelming Agnes with her eagerness. As roommates, Agnes Tachyon and Agnes Digital form an eccentric pairing due to their quirks. She offers scientific advice to Silence Suzuka regarding leg injury concerns and engages in friendly boasting with Tanino Gimlet about their protégés (Daiwa Scarlet and Vodka). Additional connections include Jungle Pocket and Dantsu Flame as friends and rivals, and Air Shakur, with whom she shares intellectual common ground. Her scientific methodology emphasizes empirical data collection, including pre-race measurements of temperature, humidity, and bodily metrics. She memorizes and reproduces experiment results as a point of pride. Her special skill, "U=ma²," references Einstein’s mass-energy equivalence (E=mc²). She sources materials like 18-liter ethanol drums and excessively sweetened whipped cream, receives overseas packages, and impulsively buys ill-fitting clothes online. Her phone background is plain black to reduce nighttime screen glare. Her background draws from the real-life racehorse Agnes Tachyon, an undefeated Thoroughbred whose career ended prematurely due to a tendon injury after four dominant wins, including the 2001 Satsuki Sho (Japanese 2000 Guineas). This earned him the epithet "Phantom Triple Crown," mirrored in the character’s unrealized potential and focus on transcending physical limits. The character’s lab coat incorporates design nods to the real horse’s red/blue striped jockey silks. Her earrings reference her real-life dam Agnes Flora’s five wins out of six races. Post-retirement, the real horse became a leading sire in Japan, paralleling the character’s enduring influence. Trivia highlights her "Ultra Sweet Tooth" and aversion to bitterness, leading her to consume copious sugar to fuel her intellect. She cuts her own hair when it grows too long. She participates in the "JAM" trio with Jungle Pocket and Manhattan Cafe. Her name derives from tachyons, theoretical faster-than-light particles.