Shin'ichirou Morisaki struggles to keep his deceased mother's family-run café afloat, working tirelessly alongside his younger stepsister, Kotomi. This heavy burden fell upon them after the unexplained disappearance of their father, a scientist ostracized for his deep research into android technology, leaving the siblings battling workload and financial hardship.

Their precarious existence is shattered when an android girl named Arisa crashes through the café's ceiling. Overwhelmed and initially resistant, Shin'ichirou turns to his grandfather—whose own knowledge connects to his father's android work—for the technical guidance needed to activate Arisa. He becomes her designated master.

Arisa's persistent clumsiness, like spilling food on patrons instead of serving it, constantly frustrates Shin'ichirou. Yet, despite this friction and the ongoing disruptions caused by her ineptitude, his stance slowly shifts from rejection to acceptance. Amid the slapstick chaos her arrival triggers, Shin'ichirou begins to see Arisa not just as an android helper, but as an essential part of their family.