I'd like to have proof of distance between municipal bus stops.

You can print it on your own via the City of Yokohama, Transportation Bureau route timetable search system. Please download and use the "distance / fare certificate" of the route search result.
[Operation method]
①https://navi.hamabus.city.yokohama.lg.jp/koutuu/pc/map/Top?window=busLocation
Get access to it.
②Select the fare and route tab, and enter the departure point and destination shown on the left side of the screen.
③The path will be displayed in the search results. Cash and IC fares are displayed in red on the right side of the screen, and you can download the certificate by selecting "Distance / Fare Certificate" below it.