There's something lovely and relaxing about this book's easy-pace and slightly old-fashioned depiction of the simplicity of childhood, where the reader really feel as if s/he is in the mind of a funny and lovable seven-year old. Lukas is delighted to get a cat for his seventh birthday but the cat goes missing and the story covers the loss of his much-loved pet, and the way this charming little lad copes with it and moves on. Obviously, therefore, there is an inherent sadness throughout but it is covered with sensitivity and good humour so the feel of the story is consistently light-hearted and gently amusing. Although this book would be particularly apt for children who have lost a cat or other pet, it will touch a chord with everyone, and is suitable for the most sensitive child, from age 5 or 6.
And if you enjoy this, as I am sure you will, then try David Henry Wilson: Triple Trouble with Jeremy James for the same childhood humour or Philippa Pearce: A Dog So Small for more wishful thinking and vivid imaginary animal scenarios.