Japan can be quite frustrating for travelers that are used to modern conveniences. With some knowledge and cultural understanding; especially about the conbinis (Japanese convenience stores), travelers can focus on having fun and stress less about the small things in life.
Tracking down a public bathroom is not too challenging. Most subway and train stops have a public bathroom. Department stores have them on multiple floors and are generally open from 10 a.m. to 8 p.m. daily. Many city parks have public bathrooms in them. In addition, some cities have them around high tourist areas such as Dontonbori in Osaka and Pontocho Street in Kyoto. Lastly, McDonald's and conbinis (Seven-Eleven, Lawson, and Family Mart) have public toilets; however, try to be polite and make a purchase. A word of caution; carry hand sanitizers, hand cloths, and toilet paper with you as many restrooms do not have these items.
Public Trash Cans:
Believe it or not, these are very hard to find. Consider yourself lucky if you stumble upon one. Japan is one of the cleanest places you will ever visit, but don't expect a place to dispose of your trash on the streets. Your best bet to find a trash can are fast food restaurants, outside conbinis (or inside by the coffee dispenser), vending machines for drink bottles, and around train platforms. You also can find one between cars riding a Shinkansen. A good tip is to use the plastic bag given with a purchase at conbinis as your trash bag while sightseeing.
It is very easy to find an ATM that accepts your international debit card if you know where to go. The best place to withdraw cash is at Seven-Eleven. Each store has a machine that accepts foreign cards for cash withdraw. Standard bank fees apply, but it is easy to find one with Google Maps or walking around town. You can also find foreign card friendly ATMs at central Japan Post Offices and some other conbinis. Japan Post Bank has a website with English maps of their ATMs found in many locations around Tokyo.
Food & Drink Options:
Conbinis have a vast quantity of delicious foods inside. You will find inexpensive onigiri (rice and a filling wrapped in seaweed), snacks, sandwiches, salads, and more. The drink selection is massive with coffees, teas, soft drinks, water, beer, wine, and even liquor. Conbinis offer fast, affordable, and convenient items for travelers to grab and go. If you want to know more about conbinis, read this great article.