Jiro (Jiro Sato) is a 32-year-old man who doesn't have a job. He lives at his parents' house and doesn't go outside or socialise with people. After the death of his father, Jiro's mother runs away and leaves behind a 6 month dog named Ichiro and some clues for Jiro. To find his mother, Jiro has to venture out into the world.

　　这是一只出生仅两个月的小狗和一个三十多岁的中年浪荡男的故事。

　　芝二郎，35岁，虽然名字叫二郎，其实是家里的独生子。一直在父母的照看下过着悠闲日子的芝二郎并不去工作，一直生活在故乡的小镇从来没有去过外地。

　　然而这样的日子划上了句号。父亲良男突然故世，母亲鞠子也离家出走了。某天，二郎外出购物，途中遇见了一只裹着红围巾的小柴犬。二郎把小狗赶走，但小狗还是跟着二郎回到了家。原来这只小狗是牵挂儿子的母亲派来的，由此招他前来寻母。

　　在朋友们的推动下，二郎带着小狗踏上了生平第一场旅行……