Dayum, really lovely, especially how almost looks like the anime but with a bit more detail around the eyes and hair, I guess it was trained by anime screenshots since there is not too much material about Sunomiya.
Here is a some information, the idea of generating this is based on this other post #16986 I liked the idea but novel AI currently looks very obsolete.
first I generated some images of Saki and Yachie being alone, I used the loras of Saki and Yachie created by Imagine Breaker
then I used IMG2IMG + DPM++ 2S a Karras sampling method to blend the background into a single one. this was the most difficult part because some things the AI redrew better, but other parts were worse, it happened a lot with the face or the skirts. after generating 63 different images, I chose this last one, ironically 63 is my lucky number. https://cdn.discordapp.com/attachments/1042523770360967238/1109310593355227168/00065-SomethingV2_2_1326128075.png
then I used inpaiting to add Yachie's turtle shell and dragon tail, and improve Saki's wings and horse tail, this is the final result alternatively I made a different version that includes a hand drawn Lightning glare by me.
and before you say anything else, I improved the fingers on both versions, it's not perfect, but it's better than broken fingers.