Well, you will not find this  in Izakaya. I don't remember how the tradition got started but this is a  seasonal food we eat every year when blueberries arrive in the market.  We always consider blueberry 
pancakes as  an announcement that summer has arrived. They are also associated with  having a good time eating breakfast out on the deck on a nice summer  morning. It has been blueberry season for some time.  In the U.S. this  type of quick cake made in a pan or on griddle is usually called a  pancake but they go by many other names such as hot cakes, flap jacks,  or Johnny cakes.  For some reason, however, in Japan they are called hot  cakes or ホットケーキ. As a kid, I thought the only way to make hot cakes was to buy a 
hot cake mix in a box or  visit "Snow brand" ice-cream parlor  
雪印パーラー with my father in downtown  Sapporo (Don't tell Mother). Apparently, 
they no longer serve hot cakes. Now, there is no reason to buy 
pancake or  hotcake mix or frozen batters. We almost never visit 
IHOP, either.
We  tried several different recipes for the batter and came up with this  combination. This produces a very light and fluffy pancake. We have a  sort of division of labor in their production; my wife makes the batter  and I cook the pancakes and both of us "install" the blue berries.

 
An  average American guy (you know who you are) can easily eat a stack of  four of these (below on the left, this is 8 inch diameter pancake) as a  breakfast. We, however, can only pack away one each (above). (My wife  claims that as a child pancakes for breakfast were extra "special" and  she once ate ten--I find that hard to believe). As you can see, I  garnished the pancake with extra blueberries but no powdered sugar. We  usually do not add extra pats of butter either (since there is plenty of  butter in the batter). As you may know, once blueberries are cooked  they turn purple (image below right). Another thing I did not know while  I was in Japan is how good real maple syrup is compared to the fake  kind usually served there. 
Batter:  This recipe requires buttermilk which may be impossible to get in  Japan.  Plain yogurt can be substituted (add milk if the consistency is too thick), however the resulting pancake  may miss some of the taste complexity the buttermilk provides. This make  6 pancakes (8 inch in diameter).
I asked my wife to fill in here:
 
Dry  ingredients: The secret to this pancake is using cake flour (2 cups)  instead of regular flour. Add to the flour, sugar (1 Tbs), salt (1 tsp),  baking powder (1 1/2 tsp), and baking soda (1 tsp). Mix to combine the  dry ingredients. 
Liquid ingredients: 2 eggs, 2 cups  buttermilk (or plain yogurt), 2 tsp. butter melted. Use a fork to  scramble the eggs. Add 2 tbs of the buttermilk to the eggs and mix to  temper them. Add the egg mixture and melted butter to the rest of the  buttermilk. Add the buttermilk slowly to the dry ingredients whisking in  a few quick strokes to make a smooth batter (don't mix too long or they  will get tough) 
To cook: I usually use 4  identical 8 inch non-stick frying pans. I preheat them on low flame for  5-7 minutes so that all the batches come out at the same doness. Instead  of butter, I use light olive oil. I add more than enough oil  in one  pan, swirl, and dump the oil to next pan and so forth. Whatever excess  is in the last pan will be poured back to a small bowl. After pouring  the batter (I use a one cup ladle) into the pan, we "install" the  blueberries by hand. We found that if we mix the blueberries into the  batter they tend to clump together so some pancakes have too many  berries and are too wet while others don't have enough. To ensure even  distribution of the blueberries we throw the blueberries individually  into the pancakes as the batter starts to set up (see above picture).  (Requires some precision in aim to get the desired effect). Actually my  wife really likes doing this. We have to move quickly to get all the  berries in before the pancake is too cooked to accept them. When the  edge of the pancake looks dry and small bubbles start appearing on the  surface, I flip it using a spatula and a flick of my wrist. I then  continue cooking for another 2-3 minutes or until done. The above recipe  produced a total of 6 pancakes of a bit less than 8 inch diameter.
For  us, it is really worth it to buy really good genuine maple syrup since  the taste is so much better than 
the maple flavored sugar water that is  so popular. We use the syrup sparingly. This is a very light pancake.  The buttermilk gives it a uniquely pleasing taste. The manual "installation" of  the blueberries means a proper distribution of sweet berry juice and  cake with every bite. It is best to eat this outside on the deck when it  is still nicely cool on a sunny summer morning with a cup of cappuccino  (We have a decent but all-manual Italian cappuccino machine. We even  roast the coffee beans ourselves).