is this Natsuko the twin sister of Chiemi?

yes

KInda weird that he doesn't at least say something like "you look like someone i know" if supposedly they are twins, then they should look the same

true but chiemi and natsuko are twins bc yk the original kings game the surviver carried the virus and married had twins then they divorced and each parent got one daughter

twins dont mean they look the same, they might look alike still since they are related but doesnt mean they are identical twins.