I assume you mean Shimbashi in Tokyo, not in Osaka.
Tama Hills would be the best bet, but about 40 of the 80kms would be on city streets just getting to/from the hills. Those hills will kick his/her ass as well if he/she is not in reasonable shape. Also, your friend would need to study the maps carefully as it'd be easy to get lost; Rapha can probably help with this as would the Tuesday Morning Training Thread on this site. No cafes to speak of mid-ride but nice ones to look forward to at the end all around central Tokyo. Le Pain Quotidien at Shiba Park is nice, and close to Shimbashi.
Other accessible routes would be boring - Arakawa, laps around Disneyland, etc.