The Yen is the weakest currency you´ll ever see but even such a trending market will eventually need a break. The chart is the weekly time frame of GBPJPY and I expect in the next couple of weeks the beginning of a larger corrective move to the downside.
Right now it is too early to say when we see the start of the retracement but around 208 - 210 is a good guess.
The BOJ has shown that the manipulate the market at times buying a lot of their own currency to prevent a collapse of their system (especially the pensions).