my favourite Bladebreakers headcanon is that when Kai enters their team, Takao is so happy to have this super-strong blader as an ally that he is willing to step on his own nosiness just to keep him around because he knows he’s already on thin ice, so Takao never enquires about Kai’s life at all, and the rest of the team follows suit, and Kai just becomes this secretive team member who does his own thing, doesn’t talk about himself, doesn’t answer questions, and it becomes so normal for the Bladebreakers to… not know shit about Kai that every new bit of information is treated as both sacred and cursed and it doesn’t help that they learn them in very random order, sometimes after many years, and completely out of context.
“Kai speaks Russian????”