Lirin is the younger half-sister of Kougaiji and the daughter of the Ox-King Gyumaoh and his mistress, Gyokumen Koushou. Her existence serves as a constant reminder of her father’s infidelity to his wife, Ratsetsunyo, yet her older half-brother cares for her deeply regardless. Lirin is a youkai princess with a cheerful, energetic disposition. She is perpetually hungry, frequently smiling, and extremely friendly, though she is also notably naive, even more so than Son Goku. Like Goku, she enjoys fighting and is a skilled hand-to-hand combatant, but she is easily distracted by food, a trait that both Sanzo and Kougaiji exploit as a running gag; Sanzo often defeats her simply by tossing her a meat bun, and Kougaiji diverts her by promising to bring her food. Despite her combat ability, she is not particularly intelligent and acts childishly.

Lirin deeply admires and trusts Kougaiji without question, and she is always willing to follow his lead. Within Kougaiji’s group, Dokugakuji and Yaone serve as her caretakers, though she frequently attempts to escape Yaone’s supervision. Her role in the story is that of a supporting antagonist, traveling with her half-brother and his companions in their quest to obtain the sacred sutra from Sanzo’s group. Although she is loyal to Kougaiji, she has a notable crush on Genjo Sanzo and enjoys spending time near him, much to Goku’s irritation. She and Goku feud whenever they meet, acting like rival siblings. Sanzo views her as little more than another monkey, but he does not yell at her as harshly as he does at Goku.

In terms of development, Lirin remains largely static throughout the series, retaining her naive and happy-go-lucky nature. In the Saiyuki Reload manga, an arc sees her nearly subjected to experimentation by Ni Jian Yi, only to be rescued by Kougaiji, after which the four half-siblings and their allies continue their journey. Her primary motivations are simple: she wants to help Kougaiji, eat, and be near Sanzo. Her notable abilities are limited to physical combat; she possesses no known magical or special powers, relying instead on her natural strength and agility. Overall, Lirin functions as a lighthearted and somewhat comedic foil within the darker narrative of Saiyuki, embodying innocence and loyalty without any significant personal growth.