Go for the Sage. I love mine. It is faster and has a better screen, which will be good for manga. The battery could be better, but is not as bad as people make out (I generally get at least two weeks of daily usage per charge (not reading manga or using the notetaking function)) and it takes no time to recharge, so it's not a big deal.
P.S. I am in Japan, too. Not that this fact has any bearing on this thread. ('_'
