I believe it was the airport batsu, and the portraits may have only been Hamada.
I think it was in the earlier parts, probably within 3 to 5. I do remember one of the artists being Man Gatarou, he's the artist for the NATSUMIIIIII one. He's a manga artist who did a few manga (warnng though: very trashy in both art and subject matter.) Some of them are being translated on Mangadex if you're curious (Crime & punishement, and happy heart company are the two I know of)
I do believe there are sub notes about each artists so you can find out about the other ones that way, I think one is just credited as street artist though.