NO. 6 Manga Omnibus 3 (Vol. 7-9) by Hinoki Kino

Shion accidentally learns that his childhood friend Safu is under arrest all because of him! Not wanting to get Rat involved, Shion sets out alone to save her. But how can he possibly infiltrate No. 6's secure correctional facility and escape with a high-priority prisoner all on his own? Includes volumes 4-6.
Binding: Paperback / softback