Artist's commentary
This and that from Watamote
The second one is Katou-san probably after something shocking happened,
Source: illust/69541964
At the end of Watamote chapter 135 Katou-san looked shocked, or maybe a little sad, so I thought at the time that maybe she could try to preserve her mental stability by hugging something she considers cute. That's what I thought.
Source: https://twitter.com/yoko_cho/status/1000016635833413633