Botan Ōhagi is a 16-17-year-old second-year high school student with a September birthday. Her early life was marked by solitude, during which she mastered the mental-state-dependent Hagizuki-ryuu martial art, inadvertently projecting an intimidating aura that caused other children to avoid her. This isolation ceased upon meeting Sakura Dōmyōji, a fellow student whose name also carries a floral meaning. Together, they established the Going Home Club at their school. The club later welcomed Natsuki Andō, Karin Tōno, and Claire Kokonoe, greatly alleviating Botan's loneliness while preserving her formidable skills.

Serving as the club's "Commander," Botan embodies stoicism, headstrong determination, and a cocky attitude. She routinely seeks extreme physical challenges to prove her strength, battling bears (brown, grizzly, and polar) and enduring impacts like chair strikes unharmed. A self-aware blood knight, she relishes combat and openly acknowledges her world's fictional nature by breaking the fourth wall. Her personality includes a comically intense jealousy, primarily directed at Karin. Karin's inherent cuteness and feminine appeal represent Botan's critical weakness; psychological attacks exploiting this vulnerability—such as Karin stating "I hate you"—can emotionally destabilize or physically incapacitate Botan despite her superhuman resilience.

As the Hagizuki-ryuu heir, Botan possesses extraordinary physical abilities. Her feats include kicking tin cans into the stratosphere, running on water, creating afterimages through sheer speed, shattering half a soccer field with a single ball kick, defeating colossal bears with minimal strikes, and karate-chopping a river in half. She demonstrates superhuman strength, speed, and durability, effortlessly withstanding punches, kicks, and furniture impacts. These powers are amplified by her mental focus through her martial art, though emotional distress—especially triggered by Karin—compromises her durability. She maintains rivalries, notably with the Hagishirabe-ryuu school's "Four Heavenly Kings."

Within the Going Home Club, Botan shares a founding bond with Sakura. She exhibits fierce protectiveness over Karin, reacting aggressively to any perceived threats of separation. Her interactions with Claire and Natsuki involve participating in the club's absurd activities, with Natsuki often acting as the straight man to Botan's antics. Her surname Ōhagi (大萩) combines "big/great" (大) and "bush clover" (萩), while her given name Botan (牡丹) means "peony," continuing the floral motif.