Haruto Ichihara, nicknamed Haru, is a popular high school star basketball player. His enduring childhood friendship with Yusuke Ninomiya began when Yusuke protected him from a dog after Haru accidentally kicked a can at it. Yusuke later helped develop Haru's basketball strategies. Haru is romantically involved with Kotona Takashina, whom he protects fiercely, even rescuing her from a Black Banner Assassin.

Haru's personality, marked by confidence, extroversion, and impulsiveness, contrasts sharply with Yusuke's. He initially dismissed Ni no Kuni as a dream, leading to reckless behavior there. His athleticism translates into formidable combat skills in that world, including sword proficiency, enhanced strength, and durability. These abilities intensify when he wears Black Banner Armor, enabling confrontations with powerful foes like Galeroth.

Driven by desperation over Kotona's life-threatening malignant tumor, Haru considers killing Princess Astrid—Kotona's otherworldly counterpart—believing it might save Kotona. This desperation leads him to align temporarily with Galeroth, who manipulates him by falsely claiming saving one life in their world dooms another in Ni no Kuni. Galeroth's deception convinces Haru to join the Black Banner Army, resulting in an attack on Evermore Castle and a near-fatal clash with Yusuke.

Haru achieves redemption by recognizing Galeroth's manipulations, rejoining Yusuke and Astrid to defeat the true antagonist, Crown Prince Sedulus Astrum. During this battle, Haru kills Galeroth using the Mornstar sword. Returning home, he discovers Kotona has recovered but no longer remembers Yusuke, who stayed in Ni no Kuni. Haru realizes Yusuke was his soulmate and finds solace in their shared history of loving Kotona.

His surname, Ichihara, combines "市" (city/market) and "原" (field/plain), while his given name, Haruto, merges "春" (spring) and "人" (person).