Tsurupettan BG Sources

Easy by @kemochiharu717: https://twitter.com/kemochiharu717/status/1510235630407540737?s=20&t=gWIwWmqHE_f5dJKA_U8YMA
Normal by 大江山: https://www.pixiv.net/en/artworks/98546135
Hard by @applejoople: https://twitter.com/applejoople/status/1459091804519735296
Authentic Lunatic by Flux3on: https://osu.ppy.sh/users/9401932
Secret Extra by kurokimono: https://www.pixiv.net/en/artworks/94609548
Extra: From the Visual Novel Umineko: Golden Fantasia
Watermelon Extra by peipoipeipoi: https://gelbooru.com/index.php?page=post&s=view&id=3847471
Extra Stage by とろろ: http://www.silver-forest.net/is.htm
Phantasm by もねてぃ: https://seiga.nicovideo.jp/seiga/im1660574