Emi looks forward to her weekend visits to her dad's new house, but she finds it difficult to leave behind her beautiful and loving Shiba Inu puppy, Rina. Emi and her brother have to get the train alone, it should be an adventure, but she's sad that her puppy can't come too. Rina doesn't understand why she can't go with Emi, even though she's tried to explain that dad's flat is too small for a lively dog. Then, during the school holidays, Emi visits her dad for four whole days, and Rina is restless, what if Emi doesn't come back! Determined to find her owner, Rina escapes and heads to the last place she saw Emi, the railway station...