Masao Sato, a timid 5-year-old with a shaven head resembling a rice ball, flinches at the slightest stress, his cheeks flushing crimson or brimming with tears under pressure. Friends affectionately dub him "Onigiri," though bullies twist the nickname into barbs. He harbors a tender heart for classmates Ai and Megumi Yamura, though Ai’s habit of treating him like a stray puppy prompts protective allies to shield his fragile emotions. Despite trembling knees, he clings to steadfast belief in love and friendship as unshakeable forces. Meticulously cataloging phone cards and insects, he crafts manga adventures inspired by Usuto Yoshii’s whimsical worlds. A self-proclaimed clean freak, he ritualistically straightens Shin-chan’s chaos during visits. Though loyal to the Kasukabe Defense Organization, his quivering voice and pint-sized frame relegate him to the sidelines. Playful jabs from Shin-chan and Nene often dissolve his composure into tears, soothed only by Kazama and Bo’s quiet reassurance. Even fleeting joys turn fragile—his prized four-leaf clover, unearthed after hours of searching, crumbled during a friend’s careless scuffle. Kidnapped by the shadowy Pig’s Hoof organization in *Dengeki! Buta no Hizume Daisakusen*, Masao clings to the group’s collective resolve, contributing through quiet cooperation rather than bold action. His survival hinges on companions’ courage, mirroring his broader role as the group’s tearful touchstone—a boy whose flickers of mettle emerge only when defending cherished bonds.