Chrom resides in a forgotten share house alongside three fellow masterless androids: Cobalt, Kei, and Neon. Adrift without purpose or understanding of their origin, they repeat empty daily routines until encountering Esora Shibaura, a genius boy whose presence triggers a dormant program within them. This activation propels Chrom and the others toward uncovering their forgotten pasts and true purpose.

To sustain themselves financially—primarily to cover electricity costs and evade forced shutdown—Chrom joins the idol unit KNoCC. They perform at Babel Tower, an entertainment venue where artists compete to stir emotions under the absolute rule of STAND-ALONE. While climbing Babel's stages yields essential prize money, these idol endeavors remain secondary to Chrom’s core journey.

A pivotal evolution in Chrom’s character unfolds as he nurtures an elderly, overweight cat. This responsibility immerses him in confronting mortality, the meaning of caring for finite lives, and the emotional bonds such devotion forges. His empathy deepens through this experience, culminating in a tribute to the cat that reflects his grasp of loss and the fragility of existence.

Chrom’s quest intertwines with expansive sci-fi themes: transferred consciousness, human-like dolls created to mend failed relationships, and systemic discrimination against emerging groups. These threads converge as he seeks the reason for his creation and deciphers the program awakened by Esora.

His story unfolds against a world submerged by catastrophic climate change, governed by a World Government that relies on androids for labor. Though this submerged reality chiefly contextualizes Babel Tower as a beacon of hope, it sets the stage for Chrom’s role in a shared fate linking humans and androids. Driven by Esora, he unravels interwoven histories and futures, contributing to the enigma shrouding their world and its concealed truths.