I have learnt to expect the unexpected when it comes to the internet.
So it's either portals or a seriously yandere gift (takes book away to reveal I-8's boobs on her chest.... then find Iku's hacked-up body in a trash compactor later missing both her breasts... and unwrap the tied-up replacement swimsuit section I-8 used to wrap her "gift" to find them)
Either this is portal play or there is serious guro happening here...
Wow my mind is sick.
Looks more like portals, look how she is pressing the books against her chest, is referring to the breasts as their own, they seem to move "naturally" and it is no injury visible or suggested.