There are 130 Choubu Chan cards to collect. Ways to check which you are missing is to look at the card collections you can trade at pawnshops. The problem is that this doesn't include all of them, and there is no way to cross check what you may or may not have. You might have missed one you thought you have gotten, or just missed a stall on vendor avenue.
Other easy to miss cards and tips:
Wu Shen temple has one
Not only do the arcades have one, but all prize exchanges too
Liu He Hall has one
Save Shenmue Building has one
The outdoor fortune teller, in the back alley beside the chemist had one.
Both temples have one, with the Broom lady's temple being harder to find. You need to search the mess made by the thugs when you first get there. You will move a piece of rubble then find a piece of paper with instructions similar to the piece of paper you got at the end of Bailu Village. The left and right directions apply the same way to the turning repository in the second part of the temple where the backer rewards are on the wall. Completing this puzzle gets you that card.
I might do a video for the Dojo YT. But I have a lot of footage to filter though first.