Nanako Itagaki (板垣菜々子, Itagaki Nanako) is a recurring character in Hajime no Ippo.
She is the the younger sister of Itagaki Manabu, who attends his boxing to cheering him on. Nanako is also romantically interested in Makunouchi Ippo, and hugs him when ever she see him. She tries to come between Mashiba Kumi and Ippo when ever she sees them together.
Nanako met Makunouchi Ippo at her house, after her brother invited him to their home to meet his family to celebrate his victory as a Pro Boxer. When Nanako saw Ippo, she hugged him while Itagaki introduced her and mentioned that she is a big fan of his. Itagaki then introduced her mother. After her father arrived, dinner was about to begin, but they said "Itagakimasu". During dinner, they continued to make puns, which made it hard for Ippo not to laugh. They continued to make jokes and Ippo tried to join them with a pun.
Nanako and her brother head to local pool to keep an eye on Ippo after hearing they heard he was soaking and resting when he reached peak physical exhaustion from training for his upcoming match with Shimabukuro Iwao. When they arrived, she saw Mashiba Kumi with him. She greeted Ippo in the pool, and boasted about her young age to Kumi. Nanako wanted to know who Kumi was and what her relationship with Ippo was, since she heard that Ippo didn't have a girlfriend.
Later, she talked with Kumi about their brothers being boxers. Nanako thought fighting men were cool, but Kumi told her that he doesn't like to go to matches because they scare her. Kumi was a little jealous of her positive attitude on it, but Nanako countered that she was jealous of her close relationship with Ippo. However, Kumi wasn't for sure on what her relationship with Ippo was. Nanako believed there was a she has a chance for her with Ippo if she works hard.
After the match, Nanako visited Ippo, when she learned that he had been sleeping the last two days. Makunouchi Hiroko told her it was okay to check in on him while he was sleeping. Nanako tried to kiss Ippo after she saw him asleep but Kumi arrived and yelled at her. She wonder why Kumi was there, but Kumi replied that she was a nurse and that she was going to take care of Ippo. Nanako started arguing with her, and Iimura Mari arrived to criticised them for being too noise. She told that she wanted to interview Ippo about his match with Shimabukuro, but not being able to while he was still sleeping. After Nanako saw Mari searching Ippo's bedroom and looking through his photo album, she joined her while Kumi didn't with out Ippo's permission.
Mari noted that based on how Kumi and her were acting, that they relationship with Ippo never made it to the bedroom stage. She told them that she was interested in Ippo, which shocked Nanako and Kumi for being so direct with them. Kumi tried to get her and Mari to leave in order to for her to take care of Ippo, but that started them fighting with each other. Hirko entered with some tea for them, and commented that when Ippo was like this, she tries to let him sleep as peacefully as she can. After they heard that, Nanako, Kumi and Mari felt ashamed and decided to leave in order for Ippo to sleep.
After Takamura's match against David Eagle, Kumi is helping Ippo and Itagaki train by timing their sprints. Itagaki wonders if Ippo is free this Saturday. Ippo, Kumi, and Itagaki Nanako mention they are free. Nanako thinks that was a close one, where she can't let her guard down with Kumi. Ippo tries to disagree, but tries to change the subject. Kumi thinks Itagaki is really into training, and mentions that he can win the Rookie King if he wins two more matches. Nanako mentions her brother is going to win, unlike someone's brother (Mashiba), but Kumi mentions he almost won it (while Ippo apologises for winning.) When Itagaki returns, he mentions he is not in the mood for fun.
Later, while Nanako at Ippo's house waiting for Itagaki, she talks to Kumi on the phone to rub her face in the fact that she and Ippo going out this Saturday. Kumi wonders why she is calling from Ippo's house, and Nanako mentions that is how her and Ippo are, before Ippo takes over the phone to explain things. He tells Kumi that this Saturday he is going to see who Itagaki will face in the Semi-Finals in the Rookie King Tournament, where he promises that he will go out with her next time.
Nanako attended Itagaki vs Imai Kyōsuke match.
After Itagaki's match with Imai Kyōsuke, he was sent to the hospital. Nanako decided to visit him. When she arrived she saw Imai get into an arguement with Itagaki over something. Kumi returned to yell at Itagaki for not resting, that causes Itagaki and Imai to calm down, which annoyed Nanako.
A few days later, Nanako is with Itagaki when he was ready to leave the hospital. Ippo arrived to pick Itagaki up in a truck, while Imai offered to walk Nanako home, which Kumi comment that Nanako should do it since they would make a good couple. That mde a Nanako a little angry, and she told Imai she thought he wasn't suppose to talk to her since he lost the match. Imai walked away determined to beat Itagaki in a rematch. Kumi thought men hate to admit they lost, and Nanako told her that if she had something to lose why wouldn't you try to keep it as she left.
with Ippo, Nanako and Itagaki becomes jealous, with the latter thinking Ippo has a cute girlfriend. Nanako disagrees with him since she doesn't think Kumi is his girlfriend.
Nanako attended Itagaki's match before Mashiba Ryō OPBF title match. During the match, Nanako teases Kumi about her "slip" problem.
When she first appeared in the story, she is pretty young, and Ippo comments on her beauty.
A 16 year-old high school student at introduction, Nanako is one of Makunouchi Ippo's biggest fans. Because of this, she views Mashiba Kumi as a rival and competes with her at almost everything. She takes any chance to be around Ippo, and even tried to steal a kiss from him once when he was sleeping after a rough match, but she was interrupted by Kumi. It's shown that she has a perverted side, as when she jumped into pool where Ippo was, she rudely grabbed his penis while stating an innuendo.
Like her older brother Manabu she is very attractive, but she also has the same love for puns as the rest of her family. Imai Kyōsuke is in love with her, but she tends to ignore his feelings as she has no interest in dating her brother's rival.