Originally uploaded to Bilibili.tv
I got too many ideas when miHoYo revealed who'd be on the banner.
Besides Kazuha the other three all have something to do with the concept of justice. Neuvillette and Yanfei are literally involved in the legal system with Neuvillette being the Iudex or judge in Latin and Yanfei being a lawyer. Xingqiu on the other hand strongly values justice and righteousness and has written many books portraying heroes carrying out justice.
And that last part is how Kazuha matches with these guys. In the Inazuma Archon Quest Kazuha loses his friend to the Electro Archon and her nigh-unstoppable sword technique the Musou no Hitotachi. By the end of the story the Electro Archon is about to strike our player character down with this same move. Motivated to protect us where he previously failed his friend, Kazuha manages to activate his friend's Vision and then successfully block the move. It was the first time someone in the game was able to temporarily activate a second Vision making it a big deal. Also after the story ends the Electro Archon realizes her mistakes and changes for the better which then greatly improves conditions in Inazuma. In other words Kazuha carried out justice and saved his homeland.