In the s1 intro, Raiha chases the quints and Fuutarou with some thing. What is this? It doesn't seem to show up in the whole of s1 and s2.
(Ideally, I'd combine all 3 images below in 1 image, but it's too large to upload.)
Based on these tweets, it appears to be some kind of cat-bear called クマティー(KUMATTY)
https://twitter.com/marine__moon/status/1088054345365520389
https://twitter.com/quintupletbride/status/1088061007006580736
Nino actually owns some Kumatty merchandise.
In manga:
In anime: