[He wasn't expecting any visitors today. So he kind of assumes it's an overeager fan or something. Though he does wonder how this person made it into his building and figured out which apartment he's actually using this evening. That vague curiosity is why he opens the door, to see... a face he hasn't seen since high school.
It isn't like they haven't met. Kasuka's an obvious way to get at Shizuo, so until the "younger siblings are off-limits" rule went up Izaya probably bothered him a few times. But he isn't a middle-schooler anymore, and he knows Izaya is breaking a big rule by showing up at all, so his emotionless stare is tinted just sliiiightly with concern.
Also it's 11pm and Izaya woke him up, so he's sort of got a bit of bed head an is wearing pajamas.]
oh noes
It isn't like they haven't met. Kasuka's an obvious way to get at Shizuo, so until the "younger siblings are off-limits" rule went up Izaya probably bothered him a few times. But he isn't a middle-schooler anymore, and he knows Izaya is breaking a big rule by showing up at all, so his emotionless stare is tinted just sliiiightly with concern.
Also it's 11pm and Izaya woke him up, so he's sort of got a bit of bed head an is wearing pajamas.]
...Why are you here?