Hidekazu has a mother who is very strict with her children, expecting them to study hard and get good marks. Her other children have all done so, but Hidekazu hates study and misbehaves in class. The story starts with him heading homeward gloomily expecting his mother's reaction to his latest misbehaviour.
'Ah, if a great big meteor would just fall from heaven and smash our house flat!' Hidekazu was thinking.
You're probably asking yourself, What's up with this rotten kid? But everyone has times when they don't want to go back home. It even happens with adults, that someone gets so that they don't want to go back to their own home and disappears halfway. Every year there are said to be 97000 disappearances. More than half of those are adults.
Under incessant pressure from his mother, Hidekazu threatens to run away, a declaration treated with derision by the family. Hidekazu runs off, thinking to stay outside just long enough to worry the family; but a sequence of accidents has him stowing away in a truck that is headed through lonely countryside in the middle of the night. Here he witnesses the driver accidentally killing a cyclist, then disposing of the body and driving off. Terrified that the driver might spot him, Hidekazu runs off as soon as the truck stops. His panicked scramble through the pitch black woods brings him finally to a lonely farmhouse, where he persuades a grumpy old man and his granddaughter to take him in.
At this point, it looks as though this is going to be a story along the lines of 'boy develops independence and finds his own character while away from his family in the countryside', with an element of adventure from the hit and run driver plotline. To some extent it is; but the book is doing something different in the scenes in Hidekazu's home, which depict a family in crisis. The tone of these parts is also very different, with scenes of conflict and intense emotion viewed through Hidekazu's eyes in the family scenes, more humour and authorial comment in the other scenes.
As an adult reader, the intenser parts had something uncomfortable to them. The antagonists in Hidekazu's family are both female (his mother and little sister), and although there is nothing implausible in their behaviour, it coincides with certain stereotypes: the mother is domineering and hysterical; the little sister is sneaky. Towards the end the autor piles more and more sins on the mother's head: she was speculating behind the family's back and mortgaged the house to cover the debts; she burns down the house by forgetting to turn off the iron. Somehow this makes it all a bit too easy for Hidekazu.