Makina Sakamaki, called Makimaki, is one of three core members of the plastic model-building club with Nee-san and Okappa. As the group's most rational and levelheaded member, she frequently acts as the straight man, countering absurd antics—particularly Nee-san's—with reason or exasperation. She completes a visual trio with her red hair contrasting Nee-san's blonde and Okappa's dark, near-blue hair. Early depictions show her wearing an elaborate tank model headpiece, a trait shared by her clubmates; these accessories gradually simplify as the narrative shifts from model-building focus.

Makimaki underwent significant weight loss after elementary school, a history that occasionally resurfaces to cause vulnerability or embarrassment in social or romantic contexts. Her romantic pursuits typically end in comedic mishaps or humiliation. Despite her usual composure, she sporadically engages in unconventional behavior like lingerie-clad appearances during exaggerated scenarios. Her role as the voice of reason faces disruption during "Okappa Days," when the typically levelheaded Okappa exhibits clingy or teasing behavior.

Her development spans the manga's ongoing serialization of over 160 chapters. The original net animation adaptation covers early material up to chapter 72. The spin-offs "MeMeMeMeMeMeMeMeMeMenhera..." and "Aoikokoro ga chikyū o waru" do not feature her in any substantial role or appearance.