Following what is now a common hostel format in Tokyo (conversions of old office buildings with a cafe-bar on the ground floor), Grids adds to the mix by throwing in four Japanese-style tatami-mat rooms (sleeping up to four; ¥20,000), as well as more private rooms with en-suite bathrooms. The dorms offer sturdy metal-frame bunks with good mattresses.
It's around a 10-minute walk to Akihabara across the Kanda-gawa. If this hostel is full, it runs a very similar one around 1km south.