Yurufuwa Suijin-sama by Rei Toma is listed as a spin-off of The Water Dragon's Bride, however, when I googled the Japanese name, nothing came up but the original series. Furthermore, I've searched under the author's name on Japanese retail sites, and no volumes of this appeared. It also has no image and no status listed, so that makes it doubly suspect.

Unless someone can find proof that this manga exists, I'm thinking that someone should probably delete the page for it.

(Hope this is the right place to post this)

It's published in bimonthly Premier Cheese! (プレミアCheese!) but there's no tankoubon out yet.
Here's a link to the latest magazine of Premier Cheese! and it does mention it.
https://csbs.shogakukan.co.jp/book?book_group_id=11740

^Okay, that makes sense. Thank you very much for clarifying things.