Haruka is a middle school student who becomes the primary human companion to Ultra Nyan, an extraterrestrial feline from the planet Felis. Her family adopts Nyan after his arrival on Earth, integrating him into their household and establishing Haruka as his caretaker. This bond places her at the center of Nyan's experiences and his mission to share "happy energy" between Earth and Felis. Her vital connection with Nyan faces a challenge when she develops a cat allergy. This forces Nyan's temporary relocation to a friend's home, a separation that devastates Nyan and causes him to lose his spirits. This relocation coincides with escalating conflicts between local cats and crows in their neighborhood park, though Haruka remains uninvolved in resolving it. Nyan previously demonstrated his protective commitment by rescuing Haruka from criminals attempting to abduct cats for illicit sale, highlighting their deep bond. Haruka's presence and well-being consistently anchor Nyan's actions and emotional stability during his documented time on Earth.