Haruki Izumo is the 14-year-old captain of Jenock's First Platoon at Kamui Daimon Comprehensive Academy and class president of Class 2-5. Academically gifted and a top LBX player, he initially projects confidence and acts as an authority figure, sometimes communicating bluntly or rudely to teammates. This strictness stems from a past incident where teammates were expelled during a mission, driving him to enforce discipline rigorously. His leadership evolves through interactions with platoon members Sena Arata and Hoshihara Hikaru. He frequently clashes early on with Arata over impulsive actions like disobeying orders during Operation Seize Oasis 3. Gradually, however, he recognizes Arata's strategic creativity and begins accommodating unorthodox tactics like drift ice maneuvers or water tower strategies, demonstrating growing flexibility and trust. His concern for teammates surfaces in quieter moments, providing academic notes to Arata and supporting Hikaru emotionally. In battle, he prioritizes their safety, notably shielding Hikaru's LBX from Gunther Yzelphar's attack at the Wall of Gigant, nearly destroying his own LBX before Arata intervenes. His development includes a willingness to break rules, like permitting Arata to interact with other countries. He overcomes his fear of failing his team through Arata's influence, adopting a softer, more collaborative approach. This growth culminates in episode 31 when he addresses the entire academy alongside Arata, Hikaru, Sakuya, and Muraku, proposing an alliance against Seredy and World Saber. His strategic acumen leads to his appointment as field commander of the World Allied Forces. He pilots the LBX Orvane, received in episode 4. After Hikaru's injury in episode 23, he upgrades to the LBX Trivhine, built by Rinko Namino and Sakuya Hosono, debuting its Tri Cannon function against Gruxeon. He also temporarily uses the Zebra Lord in Ura Ranking Battles. His combat specialties include Knight, Strider, Brawler, and Wild armor frames, with Wild being his highest proficiency. Beyond the First Platoon, he shares a close working dynamic with mechanic Sakuya Hosono, who often mediates tensions between him and Arata. He holds mutual respect with Gendou Isogai, who offers him encouragement during a paired mission, contrasting with Kaito Fuujin's silence toward Hikaru.