Instant Teen: Just Add Nuts

Instant Teen: Just Add Nuts (おとな に ナッツ) is a Japanese shōjo manga by Haruka Fukushima. The manga was published in English by Tokyopop; the Tokyopop version of the manga is out of print as of August 31, 2009.

In 2009, a spinoff was serialized in Nakayoshi called おとなにナッツー (Otona ni Nattsu ni), with different characters; it has just one volume.

Story
Natsumi Kawashima is a young fifth grader who longs to grow up and become a woman. While crushing on an older hair stylist, Natsumi is embarrassed because of her age. Natsumi runs away and steals some nuts from a lady handing them out to women only in the mall. When Natsumi is eating the nuts, she notices that some of them are pink. The next morning, Natsumi wakes up with the body of a beautiful young woman. She does not notice her body transformation until her older crush, Toji Yashiki, asks her about being a hair model. They go on a fabulous date after Yashiki gives her a makeover. The next day, Natsumi is "kidnapped" by some college students and finds out that one of them created the nuts she ate earlier. Dr. Yonosuku Morinomiya, the creator of the nuts, forbids Natsumi from eating them due to unknown side-effects. Natsumi disobeys the orders to say goodbye to Yashiki. When Natsumi plans to tell him good bye, he takes her on a cruise for the salon he works at. But while on the cruise, the nuts' effect wears off but instead, Natsumi turns into a baby! Dr. Morinomiya and Natsumi's neighbor, Asuma Yoneyama, return her back to normal. Natsumi says goodbye to Yashiki for good without telling him about the nuts or her real age. Natsumi learns her lesson and as her and Asuma play videogames, she finds out that Asuma sent pictures of her as a young woman to a modeling contest so he could get a game. Natsumi gets a package in the mail and inside it is the nuts. Dr. Morinomiya sent them to her because she finished her project and the nuts no longer had side effects. Natsumi uses the nuts for the photo shoot in the Southern Islands that she had won from the contest.

Asuma is not only Natsumi's cranky neighbour but her best friend. He always tends to worry about her all the time and he cares for her a lot though he tries his best not to show it.

Karin is another character in the manga. She is infatuated and deeply in love with Asuma, that makes her somewhat jealous of Natsumi. In a bonus story, Natsumi and Asuma steal some nuts that Dr. Morinomiya specifically told them not to take. They share one of the nuts and switch bodies while during a skiing trip. Karin doesn't notice and while skiing pretends to fall over and use the chance to kiss Asuma, who was really Natsumi.

Later on in the series Natsumi finds out that Asuma actually likes her. Many letters were sent to the author because many people wanted Asuma to turn into a man.

Characters
Natsumi is a young 10-year-old girl who just wants to grow up. When she eats Dr. Morinomiya's miracle nuts, she turns into a curvy woman! Because of her "grown-up" side, she ends up getting in several sticky situations, such as almost getting married to a billionaire, becoming a model, and starting a rivalry with Dr. Morinomiya's childhood friend. Despite this, her friend, Asuma, sticks with her. In the last and final book, she gets married to Asuma, but as children, due to Dr. Morinomiya giving them Miracle Nuts that made you 10 years younger instead of the "Relaxation Nuts" accidentally. He is called "an annoying hairstylist" by Asuma. Yashiki is a hairstylist for young women. He is the first suitor for grown-up Natsumi. He tried to kiss Natsumi during a cruise. He got dumped by Natsumi after the cruise because she realized that looks aren't everything. The creator of the miracle nuts. He is often mistaken for a woman. Even though he and Nanao are rival scientists who live on different sides of the world, in the beginning of volume 4, He and Nanao get married because they realized just how much they missed each other. He has loved Natsumi ever since he was little. He gets jealous easily, especially if Natsumi is with another man. In the final book, he gets married to Natsumi. They get married as children because Dr. Morinomiya accidentally replaced the relaxing nuts with the experimental version of the Miracle Nuts, which make a person 10 years younger. He is a rich pretty boy who is a genius. He is Natsumi's second suitor. He almost got married to Natsumi, but Natsumi escaped from the chapel because she realized that money can't buy you everything in life. Dr. Nanao is Dr. Yonosuku Morinomiya's childhood friend. She is often mistaken for a man. Even though she and Yunosuku are rival scientists who live on different sides of the world, in the beginning of volume 4, she and Yunosuku get married because they realized just how much they missed each other. Karin is in love with Asuma. In a special in volume 2, she trys to get Asuma to like her by pretending to not know how to ski. She then falls on him on purpose and kisses him. He is Natsumi and Asuma's teacher. He has a bad habit of crying.
 * Natsumi Kawashima
 * Toji Yashiki
 * Dr. Yonosuku Morinomiya
 * Asuma Yoneyama
 * Bill Wentz
 * Shinobu Nanao
 * Karin Amatsu
 * Seki He has a crush on Natsumi. In a special in volume 2, he was rested next to Karin while fainted. When they woke up, Karin said, "It was destiny that we found each other all alone in that cottage."
 * Mr. Tarumizu

Japanese

 * 1) ISBN 4-06-178958-9 published in March 2001
 * 2) ISBN 4-06-178967-8 published in August 2001
 * 3) ISBN 4-06-178980-5 published in January 2002
 * 4) ISBN 4-06-178993-7 published in July 2002