Shea Haulia is the daughter of Cam Haulia, chief of the rabbitman Haulia tribe. Her pale blue hair, azure eyes, rabbit ears, and tail set her apart from others of her race. Initially dismissed as weak within her tribe, she possesses an atavistic trait granting limited precognition, primarily manifesting as danger foresight tied to her survival.

Persecution due to her unique appearance and abilities forced her tribe to flee their homeland. She sought out Hajime Nagumo and Yue after foreseeing their potential to help her people. Following Hajime's intervention against their oppressors, she joined his group despite initial reluctance from Hajime and Yue, who derogatorily called her a "worthless rabbit" for her crybaby nature and noisy optimism.

Significant personality evolution occurred through combat training and labyrinth trials. Early traits included aggressive flirtation with Hajime, encompassing attempted non-consensual advances and voyeurism, alongside behaviors like sniffing his clothes. These diminished as she matured, developing battlefield confidence and calmness while retaining her cheerful core. She evolved into a battle-focused individual with sadistic tendencies against enemies, exhibiting violent outbursts when enraged that required multiple individuals to restrain. Her determination is exceptionally strong among Hajime's companions, enabling her to overcome mental trials in dungeons like the Frost Cavern of Schnee by confronting traumatic memories.

Combat capabilities progressed from minimal physical prowess to immense strength, speed, and durability via Body Strengthening magic and relentless training. Initial survival relied on evasion, but under Hajime and Yue's tutelage, she mastered wielding the war hammer Drucken—a weapon Hajime crafted capable of extending its handle and firing projectiles. Key feats include solo victories against demon armies, defeating apostles, and killing antagonists like Mikhail and Hearst. Post-training, she demonstrated bullet-dodging reflexes, strikes generating shockwaves capable of shattering landscapes, and martial arts proficiency surpassing her weapon skills. Additional abilities include enhanced hearing, stealth mastery rivaling Hajime's presence concealment, and marksmanship.

Critical relationships formed within Hajime's group. Persistent romantic pursuit of Hajime culminated in marriage after returning to Earth. A sisterly bond developed with Yue despite their rivalry, notably when Shea attacked Yue to dispel her fears during the Schnee labyrinth trials. She exhibits protectiveness over Hajime's adopted daughter Myu and camaraderie with Tio Klarus despite disapproving of Tio's perversions. Conversely, she holds intense hatred for threats to Hajime or his allies, desiring vengeance against Freid Bagwa for injuring Hajime and expressing disgust toward Kouki Amanogawa's delusional heroism.

Post-story developments involve relocating to Earth, participating in school and community activities, and maintaining relationships across Hajime's extended family while continuing combat training.