Sources:

https://twitter.com/totonemigi/status/1123082113379487745/photo/3 - subreddit banner

http://karutaya.web.fc2.com/9-1.jpg - mobile banner

https://www.pixiv.net/en/artworks/99666146 - Yuyuko sidebar

https://www.pixiv.net/en/artworks/44290736 - Kaguya Sidebar

https://www.pixiv.net/en/artworks/31744198 - Yumemi sidebar

Byakuren sidebar image source is dead.