Bleach, Volume 2 (Bleach #8-16)

Immediately after checking into the Kurosaki Clinic with a mysterious scar on his back, the muscle-bound Chad goes AWOL. Accompanying Chad is a talking parakeet imbued with the soul of a young boy named Yiichi. It doesn't take newbie Soul Reaper Ichigo Kurosaki long to surmise that a Hollow must be involved - the strongest spirit he's faced to date. Ichigo is about to discover that not every soul is bound for the Soul Society, especially if it's tainted with innocent blood.