as far as i can tell the changelog for 1.9 is added a bunch of illustrations that can be seen in the image gallery, which funnily enough is broken
There are 3 thumbnails that aren't referenced correctly, causing a crash when flipping through the gallery. i went ahead and extracted the game's assets to get the proper file names and fixed the code. drag and replace the file in the Umichan Sentoryu 1.9\game folder and it should work (the code in the file is also was also modified to unlock the gallery)
edit: it seems like these issues are now fixed in 1.91