Hope fully tcook will look!
Well let's see....
Coffee: Anywhere from 100-500 Yen average. Fivebucks is everywhere, as are doughnut places, and trad Japanese Kisaten.
Breakfast:If you don't like what is on offer at the Swissotel then take a wander to a conbini(7/11) for a onigiri (rice ball) and a canned/bottled tea or coffee. Shouldn't be more than 300 Yen for that. If you are game ask the concierge to find you a restaurant that still does "morning service" where you get a modified American breakfast for about 5-700 Yen.
Lunch: Bento (boxed lunch), a multitude of choices and prices to fit most budgets. Expect to pay from 3-700 Yen. Noodle shops are a good value for lunch as are most restaurants. Noodles from 250-1000 Yen a bowl(depends on place and what you order), you can ask for more noodles if you have soup remaining "free". Swank restaurants often have discount menus for lunch that are extremely good value. Sushi, can be had for about 150 Yen for normal stuff, price goes up according to fish quality.Cheapest would be at sushi conveyor place. Or failing that try and get to a fish market early in the AM to try !
Dinner is Yakitori, kushi-katsu, negi-yaki (savory pancake), Yaki-Niku. About 3000 Yen to eat your fill including a mug of draft beer or a glass of Japanese sake /shochu. Usually pricier if you want Japanese marbled beef at a steak teppan place.