Chikako Tokorozawa, a teenager, helps her parents run their pet shop where animals thrive under the family's gentle care. She shares a deep connection with her German Shepherd, Rin Tin Tin, perceiving his unwavering presence—shadowing her to school, guarding her sleep, and seeking closeness—as pure loyalty. Unbeknownst to her, Rin Tin Tin conceals intense romantic and sexual yearnings toward her.

Socially isolated at school, Chikako endures peers openly gossiping about Rin Tin Tin's obsession, including rumors of an interspecies relationship. Oblivious to these whispers, she faces only one concerned teacher who questions her solitude and home life. When Rin Tin Tin attempts mounting or breaching her boundaries, Chikako reacts with physical violence, kicking or slapping him away.

Beneath this rejection lie suppressed emotions. She actively pursues human romantic or sexual partners to divert herself from conflicted feelings toward the dog. A blush after kissing a seal during a beach trip subtly hints at buried interspecies attraction. Gradually, she toys with the idea that dogs might be more than companions, though this remains ambiguous. Her family and social circle openly endorse or accept a potential bond with Rin Tin Tin, starkly contrasting the teacher’s attempts to intervene.