[ listening to: The Rippingtons "paradise"]
Rather then list up all of the convenience stores in Japan, I will only highlight one where I take care of all of my personal needs. This is because all of them provide the similar services.
Introducing Family Mart. Or, ファミリーマート The ubiquitous chain shop in Japan that sells just about everything you need 24 hours a day, and everyday of the week. You just pull up next to the place either on a bike or a motorbike, whichever. No problems. Pop-in, grab whatever you need then leave. The cashiers are fast and well mannered, too. Forget what some idiot foreign people may say about how these acts of kindness are processed. It really doesn't matter. The point is is that the service is quick, timely and the customer service is great.
Unlike in the States where I was limited to junk food selections and personal services, and the occasional asshole at the counter, the Japanese convenience store chains provide so much more in terms of service and customer friendliness. I pay all of my bills here in cash. I can even pay my taxes here - both state and local! I also love picking up my movie, concert, and club tickets here. Overnight bus tickets can be purchased here, as well as airline tickets, as well. I can even have stuff delivered to the nearest Family Mart.
When I was in between addresses, I had a parcel shipped to the nearest Family Mart where they held it for me. When I came to picked it up, they rung up the delivery charge, and I paid it and was on my merry way. It was great. I vaguely remember, but I had some friends ship their skis up to a ski lodge via Family Mart using a 3rd party delivery service. When they arrived to their hotel the skis were there behind the counter. What convenience.
Another thing, the food is great. Anyone who's lived in Japan long enough know that food purchased here, or any convenience store in Japan, is good. The finger foods like Japanese style fried chicken and fried potatoes are better then expected. There's even the occasional selection of sushi you can get from time to time, as they tend to sell out quickly.
I love the magazine lineup as well. From popular tech mags to soft porn, you name it. Frozen food selection is good, and with all the seasonal desserts and parfaits. The dry goods selection is also decent with a large variety of cup noodles all reasonably priced. There're a variety of lunch boxes and teas, alcohol, and coffee. You can even buy cereal and canned goods. I do not know how American convenience store chains have changed since I was back in the states, but rest assured, you won't find a better service than Family Mart.