Bai Yin, originating from China, was the elder brother of Bai Jin. Both brothers possessed puppetry skills and journeyed to Prague seeking alchemical mastery to animate puppets. In France, they encountered Francine, sparking a mutual affection initially pursued by Bai Jin. Bai Yin later proposed upon witnessing Francine's kindness towards orphans and the disabled; his brother overheard this proposal in church.

After Bai Jin kidnapped Francine, Bai Yin searched for nine years, finally locating them in Quiberon, France. He discovered Francine imprisoned and fatally ill due to village persecution. Working independently from Bai Jin, Bai Yin developed a cure called Aqua Vitae using the Soft Stone. Before he could administer it, villagers set fire to Francine's cell. Reunited with Bai Yin, she chose to die content. Bai Yin consoled his brother by noting Francine's care had prevented escape attempts, gifting Bai Jin a lock of her hair before departing.

Bai Yin later returned to Quiberon finding villagers afflicted with Zonapha syndrome – Bai Jin's paralysis-inducing disease requiring laughter to counteract. To cure them, he infused a well with Aqua Vitae derived from the Soft Stone. He dissolved himself into the well, merging his memories and knowledge with its waters. Drinking villagers were cured and transformed into the first Shirogane faction, dedicated to eradicating Automatons. This sacrifice passed his puppet Harlequin and mission to Lucille Berneuil.

Bai Yin's legacy endured through the Shirogane and his martial arts philosophy. Modern characters like Narumi Katō echoed his traits, utilizing Xing Yi Quan and confronting Zonapha syndrome. His Aqua Vitae and Soft Stone became central to conflicts involving Angelina and Éléonore Saiga, who inherited the stone's power. His influence persisted through the Shirogane's 200-year conflict against Automatons and Bai Jin's reincarnations.