[KarenPang]

out of print doesn't necessary means the album was a limited edition . it just means that the online CD shops have a fixed number of copies to be sold & after the target mark has been fit , it will be listed as so

but yes as what other people have said , you have many options in getting Duty from the various sites they've listed & given to you

Amazon Japan is a good place to get 2nd hand copies of Duty at literally 1 Yen + 340 Yen domestic shipping within Japan . Alternatively if you don't mind OS presses , there's always that to fall back on