Katelyn Arshi:

No. 4 is Old Madam Ming

https://youtu.be/hj4-FGZbM3Y?si=sAisBNbrt_jQaqEu&t=84

Yes.  Ooooh there are so many hard spoiler videos around that one. I got lost in them, lol.  Can I go on watching the rest of JOL2 now ???  It may feel like a re-watch, after perusing all that. 🥴 (curiosity kills the cat syndrome).  But that video was really a nice one. Extracting what is relevant to the portrait gallery to find clues for the poster above :

But some of these guys are not on the poster (the three candidates to the imperial exam), and I thought #6 might be Lin Ruofu's subordinate Yuan Hongdao (who was in fact planted as an undercover agent of Li Yunrui)  from S1 and beginning S2 until he got over his neck with the brothel and murder impeachment snare, and reappeared in ep.24.


Anyway, to the first excellent answers, here is a medal that was once sent to me by MDL which I am happy to share with you , Anthony Tumiwa (who spotted the "hidden in plain view" CPP behind the emperor, reassigned as #13.5  , and Katelyn Arshi  who also contributed so much to the Photo gallery on the drama page : thanks to both, but the challenge is still on for the remaining unnamed characters on the poster!  🤣