Kaiju No. 8, Vol. 3 by Taiyō Matsumoto

Amid a surprise assault on the base, a covertly transformed recruit steps in to protect his squad, only to be confronted by a razor-sharp vice-captain who tests his resolve in a brutal duel. As a cunning humanoid enemy manipulates events from the shadows, the Defense Force escalates its response, officially designating the mysterious savior as a numbered threat to be captured alive, even as bonds among the rookies deepen under fire.