I recently rebuilt my early '80s Bianchi (Italian, not Japanese). The fixed cup was really hard to remove, until I found this link on Sheldon Brown's website:
http://sheldonbrown.com/tooltips/bbcups.html. Basically, it took me about 5 minutes after getting home from the hardware store (with less than $5.00 in nuts, bolts, and washers) to get the fixed cup off. Highly recommended.