I took some (crappy) photos of the sketches Kishimoto did to create the grown-up versions of his characters. I'll also roughly translate (aka "the meaning is fine, just ignore the horrible English adaptation") what he says about them... Click the names to see the pictures. Note: the "LOLs" are actually in there, it's not my comment (though sometimes I do agree 8D).
Naruto Uzumaki, Sakura Haruno, Sasuke Uchiha
-Naruto: "The forehead protector is slightly wider"
"Actually, the main characteristic of Naruto's clothes is his forehead protector. In the earlier version the line used to show the "thickness" of the metal and the line of the cloth part were very close, and that made it kind of difficult to draw the eyebrows that were right under that. For this reason, I made the cloth wider. This made both the metal's and the cloth's thickness visible, plus the eyebrows are a lot easier to draw. Besides that I also removed the rolled up part of Naruto's pants and changed his shoes from sandals to high-cut boots. Showing too much the ankle looked childish, so I tried to fix that."
-Sakura: "Sakura changed from China-style dress to karate suit..."
"I changed Sakura's clothes from the previous China-style ones to a more lively karate suite style. I gave her boots and gloves. The upper part, though, still has a Chinaesque feeling to it, so as to make her more feminine."
-Sasuke: "I thought I had to make him look cool!"
"I changed my mind a lot of times in my quest to make him look cool. I tried to put a "shimenawa" (the rope, ndt) around him to preserve Orochimaru's style.. I tried a turtleneck to show cleanliness.. I tried a military uniform.. In the end I just chose Japanese-style clothes and left his chest naked (LOL)."
Sai, Shikamaru Nara, Chouji Akimichi, Shino Aburame
-Sai: "I tried to make him look interesting to a certain extent by showing his belly (LOL)"
"Since he's Sasuke's successor, I thought that he had to somehow look cool and interesting...The result is his exposed belly (LOL). I also made him look unbalanced on purpose by making the gloves different in length."
-Shikamaru: "The focal point is the forehead protector on his arm"
"I wanted him to be unique despite wearing a normal chuunin vest. That's why I decided to put his forehead protector on his arm, so that it wouldn't hide his peculiar hair line."
-Chouji/Kiba: "One similar to his dad and a ninken rider"
"As for Chouji, in the past I've drawn his father Chouza, so I thought he might just follow his style. Kiba rides Akamaru, so he has sweat-proof clothes. Like those of a ninken rider (LOL)."
-Shino: "Even Shino's bag is stuffed with bugs"
"I eventually decided that Shino must be dressed in layers (LOL). I decided not to show much his face and other parts of his body to make him look eerie. He's also a bug user, so even his backpack is full of bugs."
Tenten, Akamaru, Ino Yamanaka, Hinata Hyuuga
-Tenten: "Her design is my favorite"
"Tenten wears a comfortable three-quarter China dress. I tried to think about the ease of movement when I drew it. This Tenten is my favorite design."
-Akamaru: "Akamaru..... well, I just made him bigger"
"I just made Akamaru bigger (LOL). His face is the same as before. I never decided a specific breed for him. I just thought of him as a dog that gets bigger and bigger and that would be able to carry Kiba around."
-Ino: "She was full of bandages, so I removed them"
"The previous Ino was covered in bandages, so I first removed those. Then I thought about the ease of movement, and since she's a girl I tried to leave some parts of her body exposed."
-Hinata: "Hinata is cute-but-uncool (LOL)"
"Hinata has to look simple, so I tried to cover all of her body and to give her a "provincial" feel. She's not interested in fashion... so I do want her to look cute, but in an unfashionable way. ...Cute-but-uncool (LOL)"
Pain, Hidan, Konan, Zetsu
-Pain: "I wanted coolness and danger"
"He's Akatsuki's leader, so he has to look cool at least to a certain extent, but I also wanted him to look dangerous. Since his name is "Pain", I decided to put some piercings on his body. Kind of like a person who gives pain to himself".
-Hidan: "Bones and a scythe remind of a shinigami"
"Hidan uses curses and such, so I wanted him to look similar to a shinigami. That's why he carries a scythe and bones. I originally planned the scythe to have a lot of tricks, but I didn't have time to show all of them... (LOL)."
-Konan: "Yeah, she's obscene... but she wears clothes (LOL)"
"I'd thought since the beginning to have Konan as the only woman in Akatsuki, so I tried to make her somewhat obscene, but...... In truth, she wears the Akatsuki mantle above that (LOL). And then, she transforms into paper right away..."
-Zetsu: "I originally wanted to make Akatsuki into a group of monsters"
"Zetsu is modeled after an insectivorous plant. I originally wanted Akatsuki to be a group of individuals with close to no human characteristics. I decided to make Zetsu half black and half white to better show his double personality."
I forgot to take photos of the page with the Nibi and Sanbi, but anyway...
-Nibi: "If it was just a cat it would be too cute..."
"There's actually a youkai (Japanese folklore monster, ndt) called "Nekomata", so the Nibi was easy to imagine. With two tails.. But if it was just a cat it would look too cute, so I tried to make him more beastlike, sort of similar to a tiger or lion, to make him look more powerful."
-Sanbi: "I've always liked monsters (LOL)"
"I've always liked monsters, youkai and huge creatures. With Sanbi I tried to mix many kinds of those. Its body recalls a turtle, and its tails are modeled after shrimps."