The new Genshin Impact Xiao trailer fleshes out the history of the upcoming 5-star character and his connection to the geo archon Zhongli, and it may have also hidden another 5-star character in plain sight.
Xiao has always been described as a demon slayer, but this trailer specifies that he was one of five Yaksha warriors summoned by Zhongli to deal with the demons in Teyvat. Of these five Yakshas, Xiao is the only one that's still active. Three are apparently dead, but one is simply unaccounted for, leaving them open for a potential appearance in a future update. If we do eventually meet this missing Yaksha they'll likely be a playable character, and given the reputation of the Yaksha, they'll almost certainly be a 5-star at that.
In the in-game lore book Yakshas: The Guardian Adepti (archived on Honey Hunter), the five Yakshas are named Bosacius, Indarias, Bonanus, Menogias, and Alatus. We know that Xiao is Alatus based on his constellation name and the fact that the two share the nickname Conqueror of Demons. On top of that, a passage about Alatus specifically mentions the Lantern Rite festival, a major event starring Xiao coming in Genshin Impact update 1.3.
Of the other four Yakshas, only Bosacius is mentioned elsewhere in-game. This Yaksha left a message on a tablet in Liyue, northeast of the Jueyun Karst lake. It reads: "Liyue is now at peace, but of our number, none but Alatus and I remain. And for my part, I wish to depart, to be done with this world." This message doesn't tell us who Bosacius is or what their element might be, but it does confirm that another one of the Yakshas has been to Liyue – and that they could conceivably come back. The trail ends there, though, so for now we'll just have to gush over the newly detailed abilities of the Yaksha coming in update 1.3.
Genshin Impact update 1.3 will also add more free Fragile Resin for all player
