This is from the Star Alliance Site:
Star Alliance Gold card holders and one guest, have access to any lounge around the world that is identified with a Star Alliance Gold lounge sign when departing on a Star Alliance flight, no matter which class of service they travel in. Just look for the Star Alliance Gold sign outside the lounge and present the ticket for your same-day Star Alliance flight, your boarding pass and your frequent flyer programme card featuring the Star Alliance Gold logo. Guests must enter the lounges with an eligible Star Alliance Gold member and must depart on a Star Alliance member airline, but may travel on a different flight.
Here is ANA information about Haneda, including the lounge location:
https://www.ana.co.jp/eng/dms/travel...hnd/index.html
And here is the same for Sapporo:
https://www.ana.co.jp/eng/dms/travel...cts/index.html
The extra baggage allowance applies to any flight, even just a short domestic hop.