Centered around the Imperial Palace
Roads in Tokyo can be a bit confusing to learn one by one, but fortunately there is a pretty cool system for generally figuring out your orientation. "Kan" means cycle, or in this case circle, so we have "Kan-ichi (one)" through 8.
This refers to a series of roads circling the imperial palace, located downtown next to the Hibiya area. The roads start as small circles around the edge of the palace area, and grow into larger rings as you move away from the central palace. Think of it like rings on a tree, growing larger in circumference as you move outward.
Knowing this can at least allow you to visualize how these main circular roads interact with other roads. As you can see from the map attached here, the other roads bisect the perimeter roads east and west.