A really interesting question. Looking at it logically one would actually suspect that NPC Ayana could exist. It is worth writing a brief explanation here. Ayana the Crimson Curse is a boss introduced in the latest summer update and is very similar to Owin and Tamru the Black. All three of these bosses only spawn during full moon. All three bosses are werecreatures. All these bosses respawn at short intervals. In short, these bosses are very similar to each other and use similar spawn mechanics. What's more - Owin and Tamru the Black also appear in the game as NPCs. Let's take a look at the following illustration which I present below.
That is why I think the question of user Libi is reasonable and interesting. Since so many features are shared by these three bosses it is likely that the boss Ayana the Crimson Curse also appears in the game as an NPC? After all, even on TibiaQA itself, there were times when the community discovered some NPC-related secrets. Let's try to check it out.
First of all, whether an NPC appears in the game we can check on fan sites. For example, on Tibia Wiki. After a brief research, it turns out that there is no mention of NPC Ayana on fan sites. But we don't give up let's keep looking. This time in the game itself. Most NPCs can be found in the Cyclopedia on the map. At the same time, we must have the region unlocked on the map to be able to preview NPCs.
If we don't have an unblocked area on the map then there is another secret but very efficient way to check if an NPC exists. We can open a client file called map.dat from the assets folder with any text editor and find the names of NPCs added in the last update. Take a look at the image below.
As you can see, there is no NPC named Ayana here. Not all NPCs are in this client file, but the existence of such an NPC is unlikely. The NPC Ayana would have to be part of some secret since Cipsoft decided not to reveal it in the Cyclopedia, and there is no evidence of that.
Let's move on to answer the main question:
From the available information, it seems that the NPC Ayana does not exist. At this point there is no evidence of the existence of this NPC.
Sources:
Ayana the Crimson Curse | TibiaWiki | Fandom
Owin (Creature) | TibiaWiki | Fandom
Tamru the Black | TibiaWiki | Fandom