How to Get Sashimi at Half price

I like Sashimi ( thinly sliced raw fish ).
But Price of sashimi is getting high in these days.
So I usually try to buy it at half price.

If you go to supermarket in Japan in late time, you may find sashimi sold at half price.

You can see two big Kanji symbol on the label on the package in this photo.
The word 半額 means half price. ( We pronounce it "HANGAKU" )

But I don't know actually what time they get the price down.
It is different in each days.
Of course If those sashimi are sold well, they never discount.
And, too late time those are sold out.

It depends on luck.