Just a minute and a half from Kakegawa station, Kuretake Inn might not actually be the closest, but it's still as convenient as you could hope for. One of a chain of business hotels located mostly in Shizuoka prefecture, it offers clean, comfortable rooms at very reasonable prices.
The friendly staff spoke a little English, and when I checked in they gave me an English information sheet about the hotel, as well as a gift of Hallowe'en Candy. In reception there's the "Service Corner", with extra supplies for your room, and elsewhere in the hotel there are vending machines for drinks and cigarettes, an ice machine and a coin laundry. There's also free Wi-fi throughout, and wired internet in all the rooms.
My single room was typically compact, but perfectly adequate for the needs of a solo traveler with little luggage, the usual business hotel amenities of fridge, TV and molded plastic bathroom all present. I was quite high up, so I had a nice view out over the town and the local scenery, and I was insulated from the little noise around the station.
Arrive during Happy Hour - actually five hours, from 3:00pm to 8:00pm - and you can have a free welcome drink in the little dining room by reception: this includes coffee, soft drinks and, from 5:00pm, beer, spirits and liqueurs. (You're only allowed one, so unless you have very low tolerance you won't be getting sloshed.) The room rate also includes a buffet breakfast, with a range of Japanese and western food: rice, fish and curry, pickles and salad, sausage and eggs, toast and pastries.
Kakegawa's a pretty small town, so as well as being close to the station, the hotel is close to everything else. Ten minutes up the road are the town's main sights, its castle and associated palace and residence, the Ninomaru Art Museum and the Stained Glass Museum, and on the way there's Honjo-Dori, a fun arcade of cosy little bars. On the other side of the station are two more attractions, Kachou-en bird park and the Shiseido Art House and Museum, and there are enough bars, cafes and restaurants nearby to keep you well fed and watered, though it was a bit of a walk to the two supermarkets I found.