I think you're selling yourself short when it comes to backgrounds -- they're very nice, and the beach scene is quite professional looking in my opinion. You're a bit stronger when you aren't using lines, but it's really all nice work, especially for first attempts.
I agree with most of the points made by others in this thread, but I'd like to discuss writing. To put it frankly, I think you could improve your writing a lot by simply cutting half of it. A lot of the text you have is either redundant entirely or conveys information that is mentioned elsewhere.
For example: you start by describing the surroundings of the first scene -- this isn't necessary, since you've drawn a background. Even if your background doesn't correspond entirely to the scene you want to set, I am going to imagine it more like the picture than like the description you're giving. Then, you talk about Shu being restless and unable to sleep. You don't need this as an internal monologue, because Shu tells this to the store owner later on anyway. Not only are you giving us the information twice, but it's more interesting the second time. Further on: do the contents of the backpack and Shu's attire matter at all? There are seven lines describing his lack of food, which I don't think are necessary at all, because the fact that he needs to get food is something that is established immediately when Shu and Takazu start their conversation. I think you can cut every single line before Takazu says "What're you doing here so early, boy?". Then there's subtler touches. It takes away from the pacing to establish that their houses are as close as they are, and you've already told us that when Shu said he could look over to Inami's balcony. The lines about Kiri's background could be dropped, as the very next sentence would already establish that he's a bird. It gets better after the first five minutes, but I think the entire story is full of lines you could cut to make the good ones have more impact.
The script goes as follows:
"The redacted part of the story here is that her mother was wearing some rather revealing clothes:
Short shorts slightly shorter than the ones Inami had before (it's like her family is fueled by short shorts), and a thin low-cut top.
Both of which ended up becoming all sorts of see-through when they got soaked by the orange juice."
Which I think would be funnier if you combined all this information in one line, like perhaps:
"The redacted part of the story here is that her mother's already rather revealing clothes ended up soaked and all sorts of see-through."
"The red tape actually extens further here too.
Her mother then tried with all her might to get me in a shower with her.
Insisting that she could lend me some of her husband's clothes while mine were being dried.
No amount of physical contact was saved from her part during all this, mind you.
It took some sweet talking and careful strategizing to be able to get her to let her eyes off of me for a moment, but I managed to do it.
And then I bolted out of there as fast as I could, still half-dressed.
Thankfully no one saw me."
Which could perhaps be something like:
"What I also don't mention is that I could only barely bolt out before her mother could drag me into a shower with her."