Gao Mikado attends sixth grade at Aibo Academy. He embodies the persona of the "Mighty Sun Fighter," inspired by a comic from his late older brother, Yota Mikado. This role involves reversing his jacket to display a sun symbol and defending those facing injustice. His attire features a reversible black and indigo jacket revealing an orange and yellow sun design, a scarlet undershirt with another sun symbol, decorative white bandage wraps on his forearms, indigo sweatpants with a yellow stripe, and white shoes. He wears a torn student cap adorned with a sun ornament and sports short black spiky hair featuring distinctive red spikes. Naturally optimistic and kind, Gao deeply values friendship, believing Buddyfighting builds bonds between people. He demonstrates a strong protective instinct, refusing to ignore those in need. However, he harbors a deep-seated violent temper fueled by childhood trauma; this manifests as aggressive recklessness when friends are threatened. The trauma stems from accidentally injuring an opponent during martial arts training, triggered by his obsessive need to win. This resulted in lasting guilt and fear of reverting to that win-at-all-costs mindset, causing him initial reluctance toward competitive Buddyfights. His Buddyfighting journey awakens after drawing a Buddy Rare card in class and receiving a Core Deck Case from Tasuku Ryuenji. Despite being a novice, he defeats experienced opponents like Tasuku and Tetsuya Kurodake in early matches, displaying strategic thinking and natural talent. He forms Team Balle du Soleil with Baku Omori and Kuguru Uki for tournaments including the ABC Cup and Gaen Cup. Gao's initial buddy is Drum Bunker Dragon, though their relationship strains when Drum temporarily departs, doubting his abilities compared to Gao's growth. Gao later partners with Dragon of the Sun, Bal Dragon, in Triple D, adopting a Sun Dragon deck and acting as a mentor to the newborn dragon. In Buddyfight X, his buddy becomes Demon Lord Dragon, Batzz, utilizing a Thunder Empire deck featuring the Overturn mechanic. During the GGG Cup in All-Star Fight, he employs a deck incorporating all three of his buddy monsters. Gao significantly impacts those around him, often inspiring positive change. His actions lead characters like Jin Magatsu to abandon deliberate losing, Genma Todoroki to understand the true meaning of the Mighty Sun Fighter, and Noboru to overcome indifference. Even rivals like Rouga Aragami eventually acknowledge him due to his unwavering belief in friendship through Buddyfighting. However, his rapid skill growth and frequent victories sometimes negatively affect close friends like Drum and Kiri Hyoryu, contributing to their temporary departures and struggles with inadequacy. His character arc culminates in marriage to Paruko Nanana and relocation to America with their children after the GGG Cup. Before departing, he envisions a future Buddyfight involving his son, Yuga Mikado, and Gargantua Dragon. Gao appears as a crossover character in the "40-Shūnen da yo! Coro Coro All-Star Shōgakkō" commemorative net anime, attending an elementary school alongside other famous characters from Coro Coro Comics publications to celebrate the magazine's 40th anniversary.