Mahoro Shimano resides on Nabu Island with her younger brother Katsuma Shimano. After their mother’s early passing and their father’s frequent off-island work, she shoulders responsibility for Katsuma’s well-being, developing a fiercely overprotective nature. Despite Katsuma’s admiration for professional heroes, Mahoro greets them with skepticism, initially dismissing their abilities as inflated. She is a small girl with dark brown eyes and straight brown hair tied into pigtails using dark pink bubble-shaped bands. A distinct patch of freckles crosses the middle of her face. Her typical outfit features a pink dress with dark pink overall straps and buttons layered over a black tank top, completed by white sandals. Her Quirk, Hologram, projects realistic illusions. She first uses it mischievously to undermine Class 1-A’s reputation in Katsuma’s eyes—creating a giant praying mantis illusion at Mount Shiroyama’s ruins and falsely reporting Katsuma missing to test hero response times. Her dismissive stance stems from fears for Katsuma’s safety and belief in their absent father’s superiority over any professional hero. When the villain Nine attacks Nabu Island targeting Katsuma’s Cell Activation Quirk, Mahoro’s perspective shifts dramatically. After their home is destroyed, she projects an illusory stone lion to shield Katsuma from Nine, though the villain sees through it. Following Izuku Midoriya’s intervention, she alerts others to their danger by projecting a massive cartoonish image of the wounded hero. During the conflict, Mahoro witnesses Class 1-A’s relentless efforts to protect the islanders, including Katsuki Bakugo shielding her from harm. She watches Katsuma exhaust his Quirk healing injured students, cementing her growing respect for heroism. Her protective instincts surge when Nine takes her hostage to force Katsuma’s Quirk surrender—a threat that ignites Katsuma’s courage. The siblings’ shouted encouragement from safety reignites Izuku and Katsuki’s resolve during their climactic battle against Nine. After the conflict, Mahoro joins Katsuma in thanking Class 1-A, reflecting her transformed view of heroes. They reunite with their father once the island is restored and the students depart.