As in A Long, Long Penguin Story, Inui lets the animal characters talk and think like people, but otherwise tries to show their lives as they really are. So, for instance, the father of the cubs has no part in raising them. We follow the mother and the two cubs from when they emerge from the snow cave they have lived in through the winter over the first years of their lives. Mishika is mischievous, Mushika is curious and inquisitive. A third cub, a girl Mashika, joins them when the brothers find her next to her mother who has been shot by hunters.
Looking at the cover, you're probably thinking that if the book is true to nature, that seal had better look out for itself, since seals are a major part of the polar bear's diet. The harsh necessity of polar life is actually a key theme of the book. The cubs make friends with various animals; but they come to understand that the lives of the animals of the arctic involve eating other animals.
"But, but, if the little human hadn't saved Mishika -" Mashika said, still shivering.
"Why couldn't the big human understand? How happy we were that Mishika and mother didn't get shot -" Mushika said angrily.
Here mother spoke, "It's something I told Mishika before, but in this harsh land of the north, since nothing is more important than finding food to survive, parents teach their children how to hunt. The humans teach their children to hunt seals and bears, bears teach their children to hunt seals and herring, and seals teach their children to hunt herring and cod. But those parents know that taking a life is something truly horrible for the being whose life is taken. Mishika, you know, destroying Oora's fellow seals is not something that I want to do. But the law of the polar bears is that the parent must at some time teach their cub to hunt seal ..... so that we can go on living."
Mishika and the other cubs were silent.
The book is aimed at younger readers. The cover suggests a reading age of seven or above, and says it can be read to children from the age of four. I can imagine that some of the material in the book might be difficult for very young readers, such as the scene on an abandoned seal hunter's ship where Mishika, whose best friend was the seal cub Oora, first sees his mother eating seal meat. The book tries to give readers and characters a chance to come to terms with this world in the summer festival that marks its climax, a magical event where all the different animals of the arctic can meet for a few days without fear of being eaten.