Bento Boxes to Go
Typical Bento Box on a Train
A bento box is like a lunch box here in the U.S. They are packed ahead of time and eaten at lunch or "on the go."
There are fancy ones made of lacquerware but there are disposable ones, too. They have compartments separating the ingredients, regardless of what they are made out of.
When we traveled for two weeks around Japan in 2011, we took trains everywhere. The train system is highly developed, fast, clean and efficient. Almost all of Japan is very safe, even late at night.