This is a service
In many countries, if you go to restaurant and you need water, you will have to buy a bottle. But not in Japan.
Once you are seated in the restaurant, immediately a glass of icy water will be served for you, even before your order is taken. This must be a great relief if you are coming from abroad where everything has to be charged. If you want another glass, just ask. They are free for refill.
Let's get free items and help them
When you walk on the streets, sometimes you may encounter a person who is distributing pocket-size tissues to the pedestrians who are passing by.It is neatly packed several pieces of Kleenex which is convenient to keep one or two in the bag.
They are also given for free because the packet contains a sheet of advertisement paper.
It's okay to put it in your pocket
Some café, restaurant or pub offer matchboxes which you are free to take, if you want.
The logo and contact are printed on the matchbox so that you can remember them, and maybe visit them again. Upon distribution of such signature item, the box usually is made to have a neat look on the design. Not to mention the quality of matches themselves.
But as in English cliché; there’s no such thing as a free lunch, you have a reason to be cautious for free items.
There is an established sales method to attract potential buyers by giving them a number of free items and eventually lead them to buy something expensive.
So it is good to be skeptical for free items but there ARE actually many items distributed for free in Japan especially when and where many people come around for the marketing purposes. Enjoy what you are in for!