All of these date from late 2022 to early 2023.
I often start projects like this by making concept arts of visuals I would like to see in the final product, even before any idea for the scenario has come to mind. This helps me find inspiration for the story, even though in this case, the storyline was less important than the rhythm and mood, in my opinion. Then, I continue refining the artistic choices while working on the scenario and storyboard until I have a clear enough idea of the art direction to start production.