Hi, how did you trigger the rainy day event? This is the first time I'm hearing of it.
Also wanted to let you know there's more variants of the library cgs depending on which place you go with both groups; the devs confirmed on their Tumblr it's currently bugged and will be patched soon! If you check the gallery and click on each library cg, there’ll be 1/3 or 1/2 available.