Rui Nikaido A boy living on Earth with waist-length blonde hair and gentle light blue eyes. He has an androgynous appearance with half-rim glasses and long hair. He is serious and kind-hearted, and despite everything, he likes Hayato as a friend (in one episode, his affinity for Hayato was 90 out of 100). When he gets angry, he is terrifying enough to make Peketz, Go, and even ghosts tremble in fear. He has an IQ of 180, can recite pi to 500 digits, and has earned a perfect score on tests countless times in his life. His birthday is December 12th. He is 176cm tall and weighs 65kg. First person: I (soft, polite). He speaks casually to Hayato and Peketz using sentence endings like "...dayo" or "...dane," but uses polite, formal language with strangers. He is well-mannered. Despite his youth, he holds a high rank in the JSDF as a Lieutenant Colonel (2nd Class Ground Colonel). He doesn't particularly enjoy exercise but can perform at a JSDF level. He primarily handles vehicle and aircraft piloting. The older brother of Hayato and Peketz.

Hayato Goonji Short red hair and green eyes. He looks like a delinquent (or rather, someone suffering from 'eighth-grader syndrome'), but he has a completely pure personality. His inner thoughts are always leaking out. He tries various things to become popular with girls, but it rarely works. He always enters Rui's house through the front door. His birthday is July 26th. He is 173cm tall and weighs 56kg. First person: I (rough, casual). He has a mischievous way of speaking, using endings like "...daze!" or "...dazo!" He becomes very intense when it involves his best friends. Refers to Rui as "Aniki" (Big Bro) and Peketz as "Peketz." Despite his youth, he holds a high rank in the JSDF as a Major (3rd Class Ground Colonel). Because he is athletic, he is constantly on the move and doesn't mind getting injured. Rui's younger brother and Peketz's older brother.

Peketz A cheerful boy with red eyes and slightly long yellow hair. He's a bit mischievous but knows how to behave when the situation calls for it. He is great at video games and his favorite food is hamburger-flavored potato chips. Birthday: October 10th. He is surprisingly light for his appearance. First person: I (soft, boyish). Height: 170cm, Weight: 50kg. He is talkative and energetic, sounding a bit rowdy. He gets very protective of his best friends. Refers to Rui as "Ni-san" (Big Brother) and Hayato as "Onii-tama" (Big Bro-woc). Despite his youth, he holds a high rank in the JSDF as a Major (3rd Class Ground Colonel). His reflexes are decent and he moves very well; his small stature makes it easy for him to hide in shadows. The youngest brother of Rui and Hayato.