The central conflict in 'Black Bullet' Volume 7 really narrows its focus to Rentaro and Enju, almost to the exclusion of everyone else for long stretches. It's their dynamic that gets put through the wringer, especially with the fallout from the events at the end of Volume 6. Enju's condition is the ticking clock for the entire plot, and Rentaro's desperation to save her drives every decision he makes. You see a much rawer, more vulnerable side to him here, far from the strategic fighter of earlier volumes.
Kisara Tendo does get significant page time, but it's mostly in a support and logistics role—mobilizing the Tendo Civil Security assets, trying to back Rentaro's play from HQ. It feels intentional, like the author isolating our main duo. The main new players are the doctors and researchers at the underground facility, particularly Dr. Nayu Kagetane, who becomes the key exposition source on the Cursed Children and the Gastrea virus. Her cold, analytical perspective creates a fascinating contrast with Rentaro's emotionally charged mission.