Many hotels will give you access to their spa, pool, and health club facilities if you arrive before check in time. The same applies if your reservation gives you club lounge access. However, note that many hotels in Japan (and some other parts of Asia) charge a substantial fee for most guests to use the health club and/or pool.

Finally, some large international four and five star hotels have special lounges for guests to use before check in and after check out. Typically there are shower facilities, coffee/tea, newspapers, and comfortable places to sit to work or read. I know that some hotels in Tokyo have this feature and it wouldn't surprise me if the same is true of the ANA Intercontinental.