Your browser does not support grid, so will not be supported. Hover over your browser version to see if there is a way to enable potential support. Sorry, I am no longer able to justify working on making the layout work on older devices.
It's implied that this is an imposter (I haven't read the manga so I'm assuming based on what Sora said) but I'm not 100% sure so I tagged both kasuga_hijiri and disguise.