So, I'm writing a story set (so far) in Japan around 1990s. The main character is a 6-year-old boy.
What I'm trying to find out is: what's the most common tale that Japanese parents tell their children to explain them how they were born?
For example, here in Italy they tell the children that they were brought to the parents by a stork. Is there any similar story in Japan?
I'm not looking for informations about Japanese sex education, but just about those fictional, silly stories the parents tell the kids when they are too young for talking about actual sex.
Thank you very much in advance for any suggestions!
PS. I really didn't know how to search for this detail on Google or Wikipedia. I tried with "japanese sex education", "tales", "how children are born japan", and something else along these lines, but as you can imagine it didn't help...