Nogizaka Haruka no Himitsu - Season 1

Yuuto learns from his best friend, Nobunaga that the anime magazine, "Innocent Smile", has arrived at the school library. Yuuto isn't interested in anime, but he has some understanding of it from being friends with Nobunaga for so long. Requested by Nobunaga, Yuuto goes to the library to return the 6th issue of "Innocent Smile". There, he sees "Silver Star of the Night (Nuit-Étoile)", the school's no. 1 perfect girl and his classmate, Nogizaka Haruka. She seems excessively suspicious in contrast to her usual self, and the book she was checking out turns out to be "Innocent Smile"!?

After learning that Haruka is actually an Akiba-kei and a little far from perfect in her true self, Yuuto begins to feel much closer to her. For Haruka, who fears people finding out about her secret liking for Akiba-kei things, Yuuto becomes the first person to truly understand her, and they become close. However, because of that, Yuuto receives an attack of jealousy at school. One day, Yuuto is invited to go shopping by Haruka. Excited about the potential date, Yuuto happily accepts the invitation. Their destination is the holy land of the otaku, Akihabara! Excited to be in Akihabara for her first time, Haruka comes well prepared with a detailed plan to fully enjoy the holy land...

Yuuto and Haruka decide to study together for the final exam at Haruka's house. As he arrives, Yuuto is shocked by the Nogizaka's luxurious mansion. The lead maid, Hazuki takes him to Haruka's room, which fits the word "gorgeous" perfectly. After a short period of the two studying together, Haruka's little sister, Mika and her caretaker, Nanami, intrude on them. They are super curious about the relationship between Yuuto and Haruka. Mika secretly asks Yuuto to take good care of Haruka. A while after that, Yuuto is asked by Haruka to come to the Natsu-Comic during the summer vacation. However, at that moment, Haruka trips, and the Comike Catalogue in her bag is revealed…

Lately, Haruka has been worried that there might be something wrong with Hazuki. Yuuto thinks she is reading into things too much, but Mika and Nanami also agrees with Haruka that something is different about Hazuki. It was coincidently right after that, Hazuki took her personal time off. Following Mika's idea, everyone decides to follow her. Yuuto can't help but be stunned by the gap between the usual expressionless Hazuki and the Hazuki in the city shopping around at a cute stuffed animal toy shop and fancy lingerie shops. As they follow her, Hazuki finally meets with a man who walks out from a building with a bridal shop, and the two of them walk back into the building, seeming very friendly.

Right before summer vacation, a beauty named Amamiya Shiina transfers into Yuuto's class. Yuuto and Shiina have had several fortuitous encounters before. They are surprised at how many times they've bumped into each other. Shiina plays the piano as well, and the genius-pianist, Haruka, is her idol. Being active, and successful in both academics and martial arts, Shiina quickly finds her place in the class. However, the news of the swim meet stumps her. Yuuto and Haruka finds out that swimming is Shiina's weak spot, and decide to help her out by giving her lessons. Will Shiina be able to master the art of swimming and compete in to the swim meet?

Summer vacation has begun and finally, it's time for what Haruka has been waiting for, Comike! Of course Nobunaga is all ready to go, and says he'll head over there on the earliest train. It's a huge difference compared to Yuuto and Haruka, who plan to leave at 9 am. On the day of the event, Yuuto is completely blown away by the crowd, way worse than rush hour traffic, and the insanely long line of people. Haruka, too, is surprised by the crowd, but is more excited about the various doujinshi that she's been after. The two head straight toward Haruka's first choice, the super famous circle, but they also have a crazy long line. Will Haruka be able to get her favorite book!?

Haruka appears at Yuuto's door, in tears. She tells him how her father, Gentou, has returned home and has thrown away all the otaku-goods that she had been treasuring. Gentou has his mind set, and would not budge that manga and anime are an inferior form of entertainment. Haruka have been trying her best to hide her Akiba-kei hobby, but she's had enough of her father's unreasonable attitude, and runs away from home. Hazuki also accompanies Haruka as her attendant. However, it's a matter of time before they will be discovered by "Hellhound," unleashed by Gentou. Yuuto receives a call from Mika to survive for 23 hours.

With Haruka's run-away incident solved, the relationship between Yuuto and Haruka has officially been acknowledged by the Nogizaka parents. Yet, this doesn't change anything in the relationship, and they still just sit together in a room, sipping away on tea, chatting. Mika, frustrated by the slow pace of things, concludes that the main cause is Yuuto's lack of skill to take the lead in the relationship. She decides to teach Yuuto the ropes of dating in order to help her ridiculously introverted sister. As a solution, she sets up a "practice date" with Yuuto. Unaware of the situation, Yuuto is taken by surprise when he, upon meeting Mika, finds out that they are going on a date. Mika then starts to take Yuuto around, but…

It's the second semester and it's almost time for the school festival, "Hakuhou Festival". Yuuto's class activity representatives are Shiina and Yuuto, and their class decides to host a Cosplay Cafe. Haruka is a little jealous because Yuuto is always with Shiina, working on the festival. It's then that Haruka is asked for advice on how to make a cosplay costume by Yuuto. Yuuto learns from Haruka about a cosplay specialty shop in Akiba, and asks her if she'd come with him on the upcoming Sunday. Haruka, of course delighted by Yuuto's invitation, did not see any reason to refuse. However, she had already made other plans for that day and...

It's the day before the school festival. Shiina and Yuuto run into an accident while they are working hard to finalize things, and it turns out looking like Yuuto pushed Shiina over onto the floor. Haruka, by mere chance, walks in on them right at that moment. Yuuto runs after Haruka, who had run away red-faced, and tries to explain that what she just saw was just an accident and that there's nothing going on between him and Shiina. However, Haruka just answers, "I know that," and runs away again. Yuuto continues to feel awkward even as the festival begins. However, surprisingly, Haruka comes to school with a smile, like nothing ever happened. Haruka seems excited to be in a cute cosplay costume and to enjoy working at the café, but…

Yuuto has been invited to Haruka's birthday party. He goes to Akihabara by himself to get a present for Haruka, a figurine of the heroine of her favorite anime. With some help and advice from Nobunaga, who he runs into, he is able to get the figurine of Dojikko Aki-chan. The party hall that the supersonic jet takes him to is the Nogizaka Family's private resort island, directly on top of the equator. There, he sees every famous person possible in the world… This surprises Yuuto, but he enjoys the mini-vacation with Haruka and Mika in swimsuits until the party begins. However, one of the guests, Shuuto Southerland, envies Yuuto and…

The party has started and Yūto is dragged inside the party hall by Mika. While waiting for Yūto's turn to present his gift, he again bumps into one of the guests and his gift is ridiculed. Yūto becomes insecure and is about to leave the party hall when an old man, who happens to be Haruka's grandfather, helps Yūto regain back his confidence....