[Yukine is walking along the border as well, with the intention to keep guard. But he's actually more interested in wanting to distract himself from the strange memories. He wants to believe they are just weird dreams but for some reason he can't shake off the feeling that there are something more.
So he's going to be a bit relieved when he sees that monster about to strike because it means he can act and stop thinking about all that for a while. He draws a line to make the monster stop.]