The self appointed "girlfriend" of Takashi who will do anything to help him make his dream come true. She is also the friend of Miho Azuki and wants to make her relationship with Mashiro come true.
Kaya was a childhood friend of Miho Azuki, making the two of them an odd pairing as Miho was always the sweet, frail, shy girl, while Kaya was outspoken and had been competing in martial arts tournaments since she was a kid. She picked up her love of fighting from her father, a retail agent. She and Miho grew closer as they got older and by middle school she had told Kaya about her dream of becoming a voice over actress, a secret that she told to Akito Takagi, which led to the relationship that the series Bakuman was based around.
Major Story Arcs
A relationship begins
The first time that Kaya is introduced, it is after Akito has revealed to Mashiro that Miho has always wanted to be a voice aver actress. While this did lead to Mashiro and Miho agreeing to marry one another and the birth of the partnership between Mashiro and Akito, Kaya is angry at Akito for spilling the secret she told him in confidence. She had assumed that Akito was asking her about Miho because he had a crush on her, however this isn't true, he was asking about her because he wanted to get Mashiro and her together, but Mashiro doesn't want him to tell her this. So, just trying to come up with some excuse to cover for this, Akito says he asked about Miho because he wanted to talk to Kaya this whole time. Kaya is stunned by this, she says she has to think about it, believing that Akito now has a crush on her.
However Kaya isn't the only one who believes that Akito has a crush on them, as she shows up at his home one day only to find another girl has shown up there on the same day. Aiko Iwase, the smartest girl in the school has shown up, believing that because Akito shook her hand and agreed to do his best in school, that the two of them were now in a relationship. Akito never wanted to date either of them but when faced with the choice of who he should go out with he chooses Kaya. Iwase leaves in disgrace and Kaya is glad to be with him now, although she does punch him first to get revenge for him going out with two girls, or at least in her eyes that's how it looked.
Kaya and Akito have an "interesting" relationship
Akito and Kaya's relationship began to develop from there, as he started asking her to come over to the studio while they work on their manga, asking her to look at their work for a second opinion, and even asking her to fight him so that he can learn how to write a fight scene. She gets inspired by his writing and decides that she wants to become a writer as well, writing short little stories online, and begins asking him for help with these (despite the fact that Mashiro feels it might stretch Akito too thin helping her with this and writing the manga at the same time). Akito at the beginning of all this really had no feelings for Kaya, but after spending so much time with her and after going out on some official dates, he actually does develop a liking for her and they share their first kiss.
During the summer Akito has to come up with a story that both he and Moritaka like or else the partnership will be over. Duriing this time he and Kaya grow closer as she tries to encourage him to do his best. By the end of the summer he and Moritaka come up with a new series titled " Detective Trap" which is picked up for serialization. After this Kaya's new roll in the series is established as she becomes the number one cheerleader for Ashirogi Muto (the name of the partnership between Akito and Moritaka, a name that Kaya gave them). She at this point will do anything she can to make sure that Akito succeeds and Moritaka and Miho get together, she even forces the two of them to finally talk on the phone after their series is accepted. From there she constantly comes to the studio to talk with the assistants and to clean up after them.
At the start of their final year in high school, all the stress of having a series and keeping up with school causes Moritaka to collapse with an infection. During this time he is taken to the hospital and refuses to stop drawing while there. Kaya believes he should stop so he can recover and even slaps Akito when he suggest that he can't stop him. She once again believes that Miho and Moritaka need to talk to each other in order to help him so she calls her up and tells her to come down, leading to the two of them seeing each other for the first time since middle school.
Gag Mangas and Marriage
Detective Trap was canceled as a result of the hiatus that it took while Moritaka was in the hospital, and Akito was feeling awfully depressed about it, leading Kaya to constantly pat him on the back and tell him to cheer up, which had the opposite effect. Akito began to disappear and would no longer answer his phone late at night, in fact whenever she tried to call he just got a busy signal. Whenever she asked if she could hang out with him he would panic and tell her that he was going to work related stuff. She started to get suspicious of what was going on but she trusted Akito and believed he was being honest with her. She agreed to meet him at the zoo one day, however when she arrived she found him holding the crying Aoki, a fellow mangaka.
She ran out of the zoo with Akito and Aoki chasing her, however she wouldn't stop to listen to them. It wasn't until Akito shouted out a marriage proposal that she was stunned enough to stop and listen to them. She learned that Akito was trying to write a gag manga for Jump but he didn't know how to write for the female POV, and Aoki was trying to write a manga for the male POV, so the two of them had been helping each other with this, and Aoki was crying because of how her former partner had recently treated her. Aoki and Kaya made up so that there was no bad blood between them, and even more surprising was that Akito wasn't going to back out of his marriage proposal, he actually did want to marry her.
Akito and Kaya move in together
Akito gets a new series published, Run Daihatsu Tanto, a gag series aimed at kids which Akito just doesn't feel very confident in, but now that it's being serialized he can get married to Kaya. First however Kaya has to have Akito go to her father and get permission to marry her. She tries to sell her fiance to her family and tells them that he wants to be a mangaka and that he already had a series published before. Her father doesn't like it though because he had a friend who worked himself to death trying to get a series published. Shockingly enough it turned out that his friend was Moritaka's uncle. After meeting with Moritaka and Akito alone, he changes his mind and agrees to let his daughter marry this upcoming writer. The two of them move in together into an apartment that her father found for them, and Akito promises to make her happy.
Iwase makes an unannounced and unwanted visit
Moving in together comes with many challenges, such as deciding on decorations. Kaya decides that she wants their bed to come with pretty little frills on it and he thinks that its like something out of a love hotel, so starting with that they decide to settle all their problems by playing a game of rock paper scissors (she wins the game to keep the frills on the bed). However their moving in celebration is interrupted when an old rival from the past, Iwase, comes back and gives them a bouquet of flowers to congratulate them on their marriage, as well as rub in their face that she now has her own manga in Jump as well. Kaya wants to know what she's playing at, why she's here to congratulate them when she was trying to win over Akito all along. Iwase says that she was only trying to beat Kaya and steal Akito back when Akito had talent, his new gag series proves that he no longer has that, which drives Kaya nuts and Akito has to hold her back.
The big day arrives
Kaya and Akito's wedding day finally comes and all their friends and family are there. Her husband's mentor Akira Hattori gives a speech about the talent that Akito and Mashiro have and it's almost like a coded message telling them to quit their current series and work on something more suited to them. Akito wants to leave to speak to him, but Kaya says she understands how he feels, but the groom can't leave in the middle of his own wedding. After this the two of them depart to their honeymoon at a hot spring, but Akito can't stop thinking about what Hattori said and about how Mashiro has been acting. He realizes that Kaya knows something she isn't saying and they resolve the issue the same way they always do, with a game of rock paper scissors, only this time Akito wins. She reveals to him that Miho told her that Mashiro wants to quit their current series, information that helps Akito realize what he needs to do.
A New Series and Relationship Troubles
Akito quits the gag series and he and Moritaka start a new series about committing perfect crimes. They experiment with how to commit these crimes by sneaking into Kaya's room late at night and swapping out a present she got for Miho with their own present, then mailing Kaya's present so it arrives at Miho's for her birthday at the same time she does. Later at Kaya and Akito's home they have Moritaka over for Christmas, which is the day that the next serialization meeting will be held. Miho sends Moritaka a cake that she made and Kaya gets jealous and decides that she wants to make her won cake (which comes out looking not quite complete and a little sloppy). However when they get the phone call that they've been accepted for serialization they don't care what the cake looks like as they all dig in.
Their team gets a group of new assistants and begin work on their new series "Perfect Crime Party" (PCP for short). It's able to become a success, ranking in the top five almost each week. However, one of their assistants, Shun Shiratori, wants to become a mangaka on his own but his rich family views it as being beneath them. They come into the office one day and demand that he give this up and come home, but Kaya and the rest of the team stand by Shun and tell the family they will make his book a success, especially her husband who says he will stand by him and make sure it's something the family can be proud of by helping Shun write the series.
Miho comforts her friend
However this quickly turns into a problem as Akito begins spending so much time working on this new series that he no longer even shows up to the studio to help with Perfect Crime Party. At home Kaya starts questioning why he isn't working with Moritaka anymore and Akito only responds by becoming cold and distant. The two of them even start getting into fights over this new series and Akito even leaves home. However even though he's her husband Kaya stands by Moritaka because she wants the two of them to remain partners and she wants Miho and Moritaka to get married. One night she finally breaks down after Akito leaves and she calls her friend Miho and reveals to her that Perfect Crime Party isn't going to get turned into an anime, meaning she and Moritaka won't get married. However Miho stays strong and helps comfort her friend.
However little does Kaya know that Akito is only doing this so he can teach Shun how to write his own series, so that way he can leave him to his own works and get back to working solely with Moritaka. After Akito reveals this Moritaka feels bad for doubting him so he asks him to punch him to make up for it. They decide that the only way to really get it all out of their system is to fight each other, and also they figure it will help them recapture some of that feeling of their lost youth. Kaya shows up just as their starting their fight and assumes it's the end of their partnership and runs in to try and stop it. However after learning what really happened she is overjoyed by the two of them getting back together.
When the series began Kaya was a strait out tomboy, serving mostly as the counter to her best friend Miho. She was also seen as being rather forceful and even a little bratty, being a bit dominating in her behavior to others. However as soon as she started dating Akito Takagi she started to show off her softer side, and she was a true romantic at heart, wanting to get Miho and Moritaka together no matter what. Because of this we started to see her become more caring and affectionate, and went from being a more dominant force who would punch Akito and ring his neck for either a small misunderstanding or for saying the wrong thing, to more of a cheerleader who was constantly encouraging Akito and Moritaka to do their best and helping them any way that she could, including cleaning up the office and inking the comics. As she grew older her tomboy nature slowly began to fade too as she became more feminine, going from being a martial arts master to wearing dresses and thinking about having a child.
However Kaya has many qualities of hers that never went away and remain constant. She always had more of a childlike sense of wonder and joy to her, much more than any of the other characters, and this remains even as she becomes an adult. And even though her temper has subsided, whenever someone is rude and cruel to her or the ones she loves, or whenever she runs into her old rival Iwase, she still needs to be held back to keep her from beating the snot out of them. But for the most part as much as she has changed she still remains the primary Dojikko character of the series.