RE: Lunch, TOTORO and Japanese Construction Pants.

Well I'm talking about the rumor that the story is inspired in the Sayama case:
"n May of 1963, at a part of Japan called Sayama, a high school girl gets kidnapped. Her older sister desperately looks for her. A few days later, they find the younger sister brutally murdered. It is said her slipper was found near the spot where they found her body and 6 Ojizou-san were near her body.

Satsuki(五月) means May(the month) in Japanese, and the name "Mei" sounds like the english word "May".

Also, at the beginning of the movie when the old lady picks up the box that was dropped, the box is labelled 狭山茶, Sayama Tea. According to the rumors, Tea field is where the older sister delivered the ransom for her sister. Near the end you will notice a man in a field working when Satsuki is searching for Mei."

Check this article about some of the clues we get in the anime:
http://www.dazeddigital.com/artsandculture/article/32059/1/unraveling-the-fan-theory-behind-ghibli-s-totoro

I believe there is something there, because Hayao Miyazaki has said that he creates his stories, characters and places inspired in his travels, also if you look at other stories he has created like "Spirited Away" on the surface it's a happy story, but if you analyze the story a bit is terribly heavy.