Based on the adventures of an imaginary character Greg Heffley, The Diary Of A Wimpy Kid has been described as a 'novel in cartoons’ that is designed as part of reading material for kids aged between eight and twelve years. reg, the kid, maintains the fact that he is not writing just a diary, but rather a journal; He also sets out to warn the reader that there will never be any 'Dear diary’ this and that in his writings.