I'll try to describe it...
When you are departing, the sequence is: ticket counter; outbound passport control; this releases you into a "general area" where you can access duty free, other shops, restaurants and the Sakura lounge; x ray security check; and sterile (?) gate area.
When you arrive, you walk thru a corridor and then are dumped into the general area. Signs will direct you to passport control. If you don't see the lounge, you can locate it as follows: do not go down the escalator to passport control; if you are at the top of the escalator, facing the escalator, then the Sakura lounge will be about 50 yards to your right.
Alternately, the Steigenberger has day rooms; I think it's a little under 100 euro. The shuttle runs every 15-20 minutes. Even more convenient but more expensive is the Sheraton which is on site. I don't know if they have day rooms.