Uh, BA is now in T2 along with JL (so that all of oneworld are together), so it's more like 30 minutes to transfer domestic to int'l. The transit desk is only for int'l to int'l transfers and you can't pick up a BA BP at Itami, so you can't use the fast connection lane. You will need to exit out to the arrival hall, go up to the departure lobby, pick up your BP from the BA check-in desk, and then enter into immigration and the international departure area. This exercise will probably take about 45-60 minutes from gate to gate (since you should be able to check your baggage through to your destination at Itami). With baggage, you might be looking at 60-80 minutes to connect.