Hirano Hasegawa (長谷川 平乃) operates as a police officer within the Genius 4 investigation unit. She maintains a consistently polite demeanor and wields a distinctive sleep-inducing karate chop in combat. Standing 1.54 meters tall and weighing 44 kilograms at 17 years old, she possesses black hair and brown eyes. During personal time, she trains regularly at a dojo, sparring against opponents significantly larger than herself. Her name carries linguistic meanings: "Hirano" combines "flat" (平) and "from" (乃), while "Hasegawa" incorporates "long" (長), "valley" (谷), and "river" (川). Her conceptual design draws inspiration from the historical figure Hasegawa Heizo.