An elite alien spy named Chikuwa has arrived on Earth with a perfectly logical invasion plan. Disguised as a Shiba Inu, his mission is to collect "cute energy," a powerful resource generated whenever humans find something adorable. Posing as a pet, he is dispatched to the home of the married couple Banjiro and Madoka Inumiya. For a time, his operation runs smoothly as he soaks up the couple’s undivided attention and affection.

Chikuwa's entire strategy collapses when the Inumiyas bring home their newborn daughter, Nene. Suddenly, the humans who were once his primary energy source now devote all their "kawaii" reactions to the baby, completely ignoring the sophisticated alien operative in their midst. The series follows Chikuwa’s increasingly desperate and comedic attempts to reclaim his status as the household's cutest resident, often clashing with his own surprisingly adorable appearance. His internal monologue as a frustrated professional spy contrasts sharply with his fluffy exterior, generating much of the humor.

The setting is primarily the warm and ordinary Inumiya household, where the domestic comedy unfolds. The main characters include the scheming yet endearing Chikuwa, the doting parents Madoka and Banjiro, and Nene, the oblivious infant who becomes his accidental rival. A fellow Geppler Alien also appears from time to time to check on the mission's progress. Notable narrative arcs revolve around Chikuwa's various failed schemes to out-cute a baby, his reluctant adaptation to family life, and the ongoing question of whether he can ever complete his mission or if he is simply becoming a domesticated pet. The series presents a low-stakes, heartwarming conflict where the fate of Earth rests not on battles, but on who can be the most charming.