[Yukine doesn't really care if this is his world or not. Protecting Sakura was his duty and he wasn't going to fail. So while she performs the cleansing rituals he's not too far off keeping guard and making sure no one interfeers with them.
He's still relieved when he sees her come out of the reservoir. He's seen the notes too and he's a bit worried about someone stealing water even if it seems pretty impossible.]
No one is going to steal our water, I won't let them. And I'm sure I'm not the only one who's gonna try to stop whoever tries that.