Fly-half Dan Biggar is the only player who started the Six Nations decider against England in March to have travelled to the Far East with Wales providing 15 of the British and Irish Lions squad.
Edwards said: "This is probably the most inexperienced Test squad Wales have ever put together so we have to be realistic with our expectations. But we are still here to win. We are the double European champions after winning the Six Nations for the last two years so we have a proud record and reputation to uphold."
He added: "It is the first time these guys have played together and the first time we have worked with many of them so we cannot expect them to play the way the team did against England or have the understanding of lads who we've coached for three or four years.
"Japan have a had a few games together, which is always preferable, and the divide in world rugby is not like it was years ago so we know we've got our hands full."
Exeter Chiefs' prop Craig Mitchell has been ruled out of the first Test at the Kintetsu Hanazono Stadium on Saturday with an ankle injury so Cardiff Blues tight-head Scott Andrews is expected to start. London Irish centre Steven Shingler also sat out training.
Caretaker coach Robin McBryde names his team on Thursday and Wales could field as many as seven new caps including versatile Ospreys forward James King, tipped to make his Test debut in the unfamiliar role of openside flanker.
Edwards said: "We've got up to 30 players out so this is a great opportunity for these guys to create a good impression with the coaches for when it comes to selecting the squad for the autumn.
"Coaches remember how well someone prepared, how hard they trained and most of all how well they played. For some of these guys, this is going to be the start of what could be a long international career, if they take their chance."
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