Makoto Tainuma hails from Hakui, Ishikawa Prefecture, sharing middle school years with Futaba Takemoto. Back then, he sported a shaved head and noticeable front teeth. Even privately during that period, Makoto crossdressed without identifying as female or exclusively attracted to males. His motivation arose from a longing to embody cuteness and universal adoration, aspiring to charm any audience.

Seeking liberation from his hometown's rigid gender expectations, Makoto relocated to Tokyo. There, he consistently adopted a feminine presentation, employing a long blonde wig, makeup, and contact lenses to reshape his appearance. This commitment underscored his drive to forge an identity centered on being perceived as irresistibly cute.

At a Tokyo university, Makoto joined an academic circle alongside Futaba, Kadode Koyama, and Ouran Nakagawa. Crossdressing remained integral to his persona, marked by consistently elegant outfits. He framed this choice plainly as enjoying such attire to achieve cuteness, finding full acceptance within this friend group.

During a Tokyo-bound flight with Futaba, turbulence from an alien shuttle attack terrified her into urinating. Makoto lent her one of his outfits after landing, demonstrating how his crossdressing extended beyond personal expression into practical aid.

Years later in a post-invasion timeline, Makoto appeared with Futaba when they met Nobuo Koyama. He relayed Kadode's prolonged disappearance and possible death amid societal collapse. Possessing alien technology enabling consciousness transfer across timelines, Makoto and Futaba offered Nobuo relocation to a past timeline twelve years prior, devoid of the alien mothership's arrival—though they themselves declined its use.