While I group Yokohama in as part of Tokyo's greater metro area, it is an independent city with its own industry and an interesting history as well. The city has provided a few self-guided walking tours through some of the more interesting neighborhoods.
The "Number 1" walk (they're numbered, though I'm not sure how they determined the numbering) takes visitors from the Motomachi shopping district, through hills full of old Western-style houses, and back around to Yamate with its long-standing nightlife.
Follow this link to view, download, or print the English PDF map and guide for this walk, provided by Yokohama city. Please let me know if this link goes bad. A list of all six walks is located at this link. These maps are almost 10 years old, but I've tried to verify as much of the information below as possible. The only change I have discovered is the opening hours of the cemetery, though the closing Wednesdays of the houses might have changed.
This is an hour-long walk, excluding time spent viewing the sights and touring inside the buildings. There are a few cafes along the way, too.
Start your hike by taking the Minatomirai Line to Motomachi-Chukagai Station, and take Exit 5. I actually walked over from nearby Chinatown after having lunch.
When you continue on the road, the first path to the right after the cemetery is Kaigara-zaka. Taking this path (and stairs) will put you between the cemetery and Motomachi Park, back to Yamate-hon-dori. Kaigara refers to shells found in the soil at the cemetery.
The second side trip is here as well; the road alongside the park's path leads down the hill on the slope known as Hitai-zaka. It will take you to the former site of a roofing tile factory.
You can take this route down and return up via the third side trip, the hill known as Daikan-zaka. This is named after a former residence of a former governor of Yokohama, though the house appears to be long gone.
Note that if you decide to return via Daikan-zaka, you should visit Stop 8 before entering Motomachi Park. Berrick Hall is located across the street from the park and Erismann's Residence:
Berrick Hall is open 9:30-17:00 (closed one Wednesday a month) and admission is free.
If you didn't decide to take the second and third side trips down and up the hill, Stop 10 is about 10 minutes down the same road. You'll also pass a fourth side trip, Shiokumi-zaka. This slope got its name due to the history of processing salt through here; author Atsushi Nakajimi taught at a girl's school at the bottom of the slope.
The downstairs rooms are furnished with tables and sofas as a museum.
From Bluff Residence 18, follow the garden around to the stairs heading down toward the buildings you see in the photos below.
JR Ishikawa-cho Station is on the street heading down Omarudani-zaka, and you should easily see the entrance soon after passing the Stagecoach bar you see above.
There are restrooms available at Motomachi-chukagai Station, at Motomachi Park (around stops 4 and 5), and at Italian Hill (at stop 11). Information boards with maps are posted at the observatory just before stop 2, in front of stop 7, and along the road to stop 10.
Harbor View Park, just west of the cemetery, has two additional historic houses (Bluff No. 111 and the British House). The Museum of Tennis is also just off the trail, in Yamate Park.
There are some vending machines along the way, but no convenience stores.
Finally, most museums/historic residences are open until 6:00 pm July through October (the cemetery and Yamate Museum do not extend their hours in the summer).
While there are multiple walks to experience in Yokohama, this was the most appealing in my mind and rightfully deserves to be the "Number 1" walk.