Ken Tazaki serves as commander of the human resistance forces battling an alien invasion. He displays a stern, authoritative demeanor befitting a seasoned military leader wholly dedicated to humanity's survival, prioritizing strategic deployment of limited resources against overwhelming alien threats.

Tazaki initially opposes Hiroshi's proposal for a counter-offensive using the incomplete PlaNet system, judging the plan excessively risky with minimal chance of success. He views Hiroshi as reckless and inexperienced, resulting in a confrontational dynamic where Tazaki actively obstructs the plan's execution.

However, Tazaki's pragmatism leads him to acknowledge Hiroshi's unwavering resolve. Witnessing Hiroshi's commitment and the PlaNet system's potential, he shifts his stance and provides critical support—authorizing the PlaNet unit's deployment and mobilizing resistance forces to reinforce Hiroshi's operation.

In the final assault against the alien command ship, Tazaki commands resistance forces, coordinating defenses and directing fighter squadrons and resources to shield Hiroshi's PlaNet unit during its attempt to breach the alien vessel. His leadership proves pivotal in enabling Hiroshi's success.

Ken Tazaki's personal background, life before the invasion, and specific fate after the conflict remain undocumented.