For Oden (in winter) and Nihon-shu, "Bar Iki" is my favourite dive. When I visited last week, they weren't serving oden during the hot summer weather (unsurprisingly). But at any time of year, the "master" will be very happy to find a sake to suit your tastes from his extensive selection.

Bar Iki
Nearest station: Ushigome Kagurazaka (exit A1)
Address: Shinjuku Ku, Tansu-machi 25
Tel: 03-3235-3044

It's up one flight of stairs from the chili-men-tei ramen shop at the Ushigome Kitamachi crossroads.

Very nearby (about 100m down Ushigome Chuo Dori) is rather unique soba restaurant. I'll put that one on another thread. Let's keep this one for oden.