Well, there's Mana's outfit from the beginning of the series, her kimono. I've thought about doing the fugitive version of it, with the torn hem. She gets done up in kimono a couple times throughout the series. Natsume, from the Bone Princess arc, is another idea. Her hairstyle is really cute.
If you didn't mind playing a antagonist, Isago from the "Village of the Fighting Fish" story has some really beautiful kimono. Her purple one is gorgeous. Rin, my character, is from the same story. I'm hoping I can convince someone to do that version of Yuta.
The problem with Mermaid Saga is the clothing in it really does look like regular clothing. The kimono are pretty but in most cases not distinctive enough to link to any particular character. That's one of the major reasons I want to do Rin: I really love the character, and her story, but her regular outfit is also unusual enough that it looks like a costume. Maybe most people won't know who I am, but at least they'll know I'm supposed to be somebody.
If you get hot easily, though, most of the kimono may be too much for you. I'd recommend Natsume out of all of them; since she's still a young girl (or looks like one), her outfit would look appropriate done in summer-weight cotton. The colors are really nice, too, bright and cheerful. I'm looking at the cover of volume 3 as I type: crimson background, large jade green circle pattern, golden yellow obi, and periwinkle second kimono (could be done as a false collar if you only wanted to wear one layer). She makes me think of a cross between Rin and Kagura from Inuyasha.
