Ren Jingūji is the third son of the prominent Jingūji conglomerate family. His mother, the famous idol Jingūji Renge, died in an accident during his childhood. His father subsequently discarded all her memorabilia, leading Ren to believe his father harbored hatred towards her. Ren salvaged one song his mother composed while pregnant with him, dedicated to his future well-being; this song became a cherished connection, and he often retreated to parks to listen to it, navigating waves of grief.

Initially, his enrollment at Saotome Academy was orchestrated by his eldest brother, Seiichiro, to leverage Ren's talents for the family business. This directive fostered resentment in Ren, who saw it as an infringement on his autonomy, despite his underlying passion for music. His apathetic demeanor manifested as skipping classes and neglecting assignments, masking this internal conflict. A carefree, flirtatious persona became his hallmark, frequently surrounding himself with admirers; terms of endearment like "little lamb" or "my lady" danced on his tongue, often directed at women, especially the protagonist, Haruka Nanami.

A pivotal shift came through Nanami's influence. Facing expulsion for failing to submit lyrics, Nanami discovered and reconstructed his discarded assignment. Her insistence that he "unleash his suppressed feelings" sparked an emotional and artistic breakthrough. He publicly performed the completed song, "Sekai no Hate Made Believe Heart," reclaiming his dedication to music and securing his place at the academy. This marked the beginning of his deeper devotion to Nanami, though his flirtatious nature persisted, now more focused.

His relationships with childhood friends Masato Hijirikawa and Ranmaru Kurosaki, both heirs to influential families, were initially strained by familial expectations. Though they distanced during adolescence, their bond endured; Ren frequently teased Hijirikawa's formality, relying on their mutual understanding. Within ST☆RISH, Ren evolved into a supportive member, prioritizing the group's cohesion and offering guidance during challenges. His saxophone became a recurring voice for his emotional expression.

In subsequent developments, including the concert film *Gekijō-ban Utano☆Princesama♪ Maji Love ST☆RISH Tours*, Ren continues as an active member of ST☆RISH. The film centers on a globally themed performance, showcasing the group's musical synergy.

Additional facets include his dislike for chocolates stemming from a childhood incident, his proficiency in Italian, and hobbies such as darts and playing video games with Ai Mikaze.