The service's map shows a map of stations: http://docomo-cycle.jp/minato/map/
Reading the JavaScript source code leads to a JSON file which contains the data with location names in Japanese:
http://docomo-cycle.jp/minato/system/data/portnavi.json
The location names in English are found by prepending 'en' in front of portnavi.json:
http://docomo-cycle.jp/minato/system/data/enportnavi.json
Each participating ward uses the same URL syntax. Replace 'minato' with the other ward(s) name for their information.
The wards are:
chiyoda
yokohama
sendai
This data is not always up-to-date, though, some stations are missing.