The Developer of the Modified Souls

Yoruichi explains that she summoned Kūkaku Shiba, who arrived with Jidanbō and Ganju to reinforce the captains against Inaba's forces. As Kenpachi and the others engage the Reigai, they send Ichigo, Kon, and Kisuke Urahara ahead. Ichigo soon collapses, his eyes darkening as his Hollow nearly takes hold, and he wakes bound in a warehouse where Urahara admits the balance between his Hollow and Shinigami powers is failing. Entrusting the Reishi collector to Kon, Ichigo lets himself be sealed away with Kidō for safety.

Urahara and Kon return covertly to the S.R.D.I. to investigate the Twelfth Division, Inaba's unit. Learning that Inaba joined the Gotei 13 only sixty years ago, Urahara combs library records for a Shinigami who vanished before that date.

Urahara pieces together that Nozomi and Inaba are both Mod-Souls based on Ōko Yushima, the original developer of the Mod-Souls, and that Twelfth Division records were erased while Tenth Division files from ninety-six years earlier were altered to hide him. Following the trail, he concludes Yushima is being held in the Nest of Maggots. There, after cutting down two Reigai, Urahara and Kon find Yushima slumped unconscious in a cell, with Urahara warning he may never wake.

Back in the warehouse, Ichigo breaks free of his restraints, now fully Hollowfied.

This anime-only episode belongs to the Gotei 13 Invading Army arc and adapts no manga chapters. The closing Illustrated Picture Book follows Hitsugaya recalling Byakuya slipping away each night at Kūkaku's home, which he assumes is training, only for the reveal to be a giant Wakame Ambassador statue.