Safety
Japan is extremely safe, with one of the lowest crime rates in the world.
You can walk on the streets and not be afraid. The country is also hospitable, clean, prompt, polite, efficient, friendly, and you can drink the tap water.
In regard to safety, many foreigners have wonderful stories of returned lost wallets. Hopefully, you will not have to report such an incident to the police, but if you do, you will find a "Koban" or Police Box at most train stations and major city intersections.
Cleanliness
In regard to cleanliness, you will find that most cities in Japan do not have garbage cans along the streets. This is because the Japanese do not eat and walk at the same time. Therefore, they do not produce trash such as paper coffee mugs, ice cream cups, or chip bags, while strolling along a thoroughfare. If you have such trash, carry it with you until you find a garbage receptacle -- usually at locations that sell such snack items or next to the ubiquitous vending machines. When you do find the trash receptacles you will notice that there will be separate bins for regular trash vs. aluminum cans and glass bottles. Throw the recyclables in their appropriate slot.