In Chinatown Detective Agency’s second case, “A Stamp of Approval,” you’re given a couple of sets of stamps and you have to figure out where they originated from. For the two identical stamps, you just have to deduce their country of origin. However, for the set of five stamps, you can get a little extra cash if you figure out not just the country where the stamps came from, but also the city where they were used. Here’s how we figured out this case.

Where are the stamps from?

One key indicator of the stamps’ country of origin is the print reading “FEN” in the bottom-right-hand corner of each stamp. Fen is a denomination of currency used in Greater China, meaning you’ll want to focus on researching areas inside China. Through some online searches, we found that the stamp originated from Manchuria, which was invaded by Japanese forces in 1931 — one year before Shanghai was attacked.

As Shanghai is one of the in-game areas you can visit, you’ll want to travel there and give the stamps to the Shanghai Philatelic Institute. Once you arrive there, the museum will thank you for returning the stamps and also ask if you happen to know where they were used.

What city were the stamps used in?

Like Tiger Lily’s stamp, you can see a circular stamp on the bottom two stamps signaling they were used, but the text indicating where they were used is cut off. All you can see are four letters: HARB. Considering what we just learned about China and Manchuria, a quick search reveals that this stamp was used in Harbin, a city once part of Manchuria that is now the capital of Heilongjiang. Type “Harbin” into the text box when asked which city the stamps were used in, and you’ll get yourself a nice bonus.