With the way the economy currently is, when people in Japan eat at fast-food places, it’s because they’re cheaper (more than the speed of the service or any other reason).
In Japan, the fast-food place that understands this best seems to be McDonalds. (I think this is the reason Wendy’s left Japan after thirty years here…because their prices were higher).
Right now, McDonalds Japan is running a 「福めくりポテト」 (“Lucky Decal Fries“) campaign.
If you buy a large-size French Fries, you’ll find a decal on the fries package. When you peel it off, the decal is a coupon that can be used to get a free hamburger, 「シャカシャカチキン」 (“Shaka-shaka” chicken), or a small Coca-Cola.
The decal will specify which of the three items you’ve won (you can’t choose from the three…it’s printed on the coupon which one it can be redeemed for), and the offer expires on 2010 February 28.
Every decal is a winner. So, if you play, you will get either a hamburger, chicken, or cola for free.
Also, if you buy a set-meal that comes with a medium French Fries, you can change them to a large Fries (so you can get a 「福めくりポテト」 (“Lucky Decal Fries“) campaign decal) for only an extra ¥40.
Tokyo Five 
Recent Comments