Rent Bleach: Series 6: Part 1 (2007)

It's back to high school and Hollow slaying for Ichigo Kurosaki, who is now officially recognized as a Substitute Soul Reaper by the Soul Society. On the day he returns to Karakura First High School, Ichigo meets an unusual new student named Shinji Hirako, who seems to know about him and his inner Hollow. When a massive amount of spiritual pressure approaches Karakura Town, Isshin and Kisuke worry that someone is attempting to build an army of Arrancars-Hollows with the power of Soul Reapers.