It's PG. The content of Brave Story contains some action and mild emotional intensity that makes it appropriate for a PG rating. There aren't any overly intense or mature themes that would warrant a G or PG13 rating.
Yes, 'A Christmas Story' is typically rated PG. It's considered suitable for a wide audience but may have some mild content that requires parental guidance for younger viewers.
A novel romance PG usually has mild romantic content without overly explicit or intense scenes. The story focuses more on the emotional connection and development of the characters in a relatively gentle and appropriate way for a wide audience.
One characteristic is that they are suitable for a wide range of ages, including younger readers. So they often have themes that are easy to understand and relate to, such as first love. In 'The Fault in Our Stars', it's about the first and only love of two young people facing a difficult situation. Pg rated romance novels also often promote positive values. In many of these novels, like 'Pride and Prejudice', the relationships are based on mutual respect and understanding, which are values that can be learned from.
Another example is 'The Ring'. A cursed videotape is at the center of this story. When people watch it, they receive a phone call saying they will die in seven days. The creepy imagery, like the girl crawling out of the well, makes it a great PG 13 scary story.