"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." Commentary tl via Danbooru.
Actually, Katou was mad, specifically at Fang Girl who mocked Tomoko and Katou's make-up job. But that certainly might lead to a good close cuddle with Tomoko. It would help here if Tomoko had the make-up on.