Very cute picture.

--) Right away, the jacket stands out to me. You've done a fantastic job making it look like leather.

--) The style is really well done. To me, it's akin to the old animated Disney style; with toony facial features, yet they're still proportionate. The anime style, for a lot of people, seems to be a comfortable go-to for drawing 'toony-yet-anatomically-correct' figures, but your style is more western than that, and I really appreciate it.
Also, she's displaying a relaxed, content expression, which perfectly fits the autumn stroll that you're depicting here. She's looking around on the ground a bit, possibly implying that she's enjoying the sights of the fallen leaves, or something related to autumn.

--) The use of color is good. Her mostly blue outfit contrasts nicely with the complementary orange background. Except... there's odd splotches of brown on the outfit. Now that I look at it, it looks like you've painted the background on top, which caused that. I would've painted the background under the girl on a different layer, or if not, at least gone in and touched up the spots where it bled over. Not a huge deal, it just makes the clothes look a bit dirty. Easy fix.
Another recommendation is to brighten up the picture a bit. It looks a little grayed out. Actually, if you really want to depict an autumn scene, you could add little splotches of light on the figure, making it look like she's standing under a tree, whose leaves would be casting a bunch of little shadows.

--) Now, the weakest part is the background, to me... I TRULY understand that having an effective background is tough to do. Usually harder than anything in the foreground. But it's still difficult for me to give this background any kind of points. It looks like she's walking away from a fire, honestly... A nicely painted background with orange/red trees and falling leaves would probably be best, but isn't necessary at all. It would still work great with simple shapes implying an autumn scene. From looking at your other work, I can see you're perfectly capable of this. For example, your "Summer Day" drawing has a really effective background. A background like that would definitely benefit here.

Overall, great drawing. After a bit of tweaking, I could say this belongs in the art portal!

Awesome job here. I can't say I know anything about the subject matter, (don't play Splatoon), so I'll critique based on what I can see.

--) Right off the bat, I love the use of colors. These particular shades of green and pink look awesome against each other, and the glow effect around the edges of the characters is fantastic! It makes the whole piece so vibrant, and makes for a lot of visual interest. I also really like Pearl's hair.

--) The shading is very subtle, but it works. The only complaint I have about that (and in the whole piece in general) is that the light source doesn't look consistent. For example, on Marina's arms, there's reflected light coming from both sides? There may be a reason for that, and forgive me if I'm missing it, that's just what I noticed. If I had any recommendations on the shading, I would tint it either green or pink, depending on the side they're on. I think that'd look great.

--) The composition is very solid. It's very clear that both characters have the same amount of importance, despite Marina being a bit taller. Both characters are centered correctly, and the background is nice and subtle, not overbearing in the slightest.

--) The style is great. I'm a huge fan of the toon, stylized kinda thing. It's toony, but it's clear you also understand the fundamentals of drawing 3D objects in 2D space, like in Pearl's crown, Marina's tentacle... things (idk what they're called), and the zippers on both of their outfits. You obviously had a style in mind, and I think it turned out really well.

All in all, I love this drawing. I may not seem that credible, considering I've only got one piece of art on my page so far, lol. But I am new here and looking to grow myself.
But yeah, you've got some awesome talent on your hands, and I've happily reccomended you to the portal ^_^