Kyousuke Mizoguchi joins the crew exploring a new island, interacting with Maya Toomi through fishing-analogy advice before plucking her from danger during a Festum attack involving an assimilated soldier. He partners with Yukie Kariya to activate the Fenrir program, pushing its timer beyond recommendations and fighting alongside her against Festum forces.

Later, he mentors trainees in aerial combat, assessing Maya's skills and framing her performance as a "graduation exam." His jet suffers a Festum attack mid-mission, forcing an ejection enabled by Maya's intervention. This draws lighthearted responses to colleagues' reprimands over perceived recklessness.

He contributes to strategic talks on deployments and resources, firmly opposing solo entries into high-risk zones like the Mir. Accompanying teams to vital locations, he later stresses battlefield testing for understanding newly integrated compatible cores.

During large-scale engagements, he commands operations like overseeing the L-Boat in the Fifth Operation Azure. Here, he orders shield deployments for penetration and coordinates Fafner unit launches. Monitoring expeditions from command centers, he voices a preference for active roles over observation.

The spin-off "Behind the Line" places him in a peaceful period as a supporting presence while former pilots transition to civilian careers, sharing scenes with others during this phase.

Throughout, he maintains the tactical "Friendly Sniper" combat role.