OK, I'm going to dust off my illustration checklist and give you as much detail as I can. Let me know if you'd like any clarifications
The link got stuck as a static image even though it is a 3D view from someone who is standing on the bridge. The angle in that static image shows the 9-story building I mentioned in the chapter, but anyway, see if this works. In any case, go ahead and have a little fun with it if you want to make it prettier than it is in real life. The story is technically set in an alternate universe anyway. The "Blooming Planet Festival" is based on the "Whole Earth Festival" in case you'd like to get a better sense of that.
So, Mokuba is actually Mokuba Kaiba from the Yu-Gi-Oh! anime, but he's 22 in my story. A few other artists have portrayed him as an adult, and here are my favorite pieces:
reference image 1
reference image 2
For Mokuba's clothes, I'd like him wearing a purple and black striped shirt like this one from the Chapter 5 illustration.
Height: 6'
Joan is my OC, and here are the images I have been using for her:
reference image 1
reference image 2 (I like the level of hair curl in this one but the darker hair color in the others)
reference image 3
reference image 4
Eye Color
Clothes: Cargo pants and green/blue tie-dye shirt like this
Height: 5'10"
Props: If the pose/angle shows it, toss in the black purse from the Chapter 5 illustration, and Joan is wearing this ring on her left hand.
Time of Day: Morning, around 9 or 10am
Here's a direct link to Chapter 48 so you can get a sense of the moment.
Facial Expressions: Joan is feeling nostalgic, and Mouba is full of awe/wonder, basically just happy.
Pose: I'm imagining Joan's back against the rails like this, and maybe you could leave out Mokuba altogether if the view is from his perspective, but with the two of them together, either have Mokuba at her side listening attentively, or something closer like this. Or if you think of a better pose, or if a different part of the chapter sounds like more fun to illustrate, you could do that instead.