Personality Haruhi is a bright, energetic and athletic high-school student. Many male students consider her attractive. She alternates between melancholy and incredible optimism, often unpredictably. Haruhi is indeed stubborn and one who doesn’t like to admit her mistakes, usually blaming other people. Also, she gets angry very easily, being an irascible and impulsive person. Her behavior was considered eccentric, and she had little interest in her classmates, at least until a certain one named Kyon "convinced" her to form the SOS Brigade. Afterward, she became more mentally stable and gradually connected with schoolmates in club activities. Powers
Haruhi has the ability to create reality (or “data”), but the power is unconscious and she is unaware of it. Just by thinking, she can alter reality. Sometimes this manifests as the ability to make something of her desires truly exist, such as closing off a remote island with fog (to enhance the atmosphere of a murder mystery). When she is overjoyed, her abilities have changed the weather, made animals speak and even changed the orbit of the Earth.
Closed Space: When her emotions become unstable, she subconsciously creates closed space and celestials which begin to take over the world, destroying things. Koizumi said that the system was born of “common sense”; Haruhi encloses the celestials in closed space to prevent destruction in the “real world”. Creating Alternate Realities: Haruhi has the ability to split and recombine reality into two alternate parallels. She even created a time loop to experience the same day over and over without it being apparent to anyone else, including herself.