"Plus they're the perfect size to be hugged!"
"I dunno they're a lot bigger than you, Shima."
Could be implying body pillow is too big for Shima, could be implying Shima is the perfect size to be hugged...
It's funny because the body pillows the two of them chose for themselves both look like each other (the cat looks like Ise, and the rabbit, like Shima). Obliviousness wins the day, I guess...
The author really seems to be setting things up for them to end up together...