As a young adult, Kaitou seems to have been a man who had a very strong passionate love for his first wife Hionaka Yuzuno. He also appears to have been a person who smiled and joked around a lot more. He was much more trusting and loving towards others before he was cheated on.
After discovering that his wife had been cheating on him almost immediately after their marriage, Kaitou seems much more closed off. He is more cynical and distrusting of others. He smiles significantly less and frowns a lot more. He does smile sometimes though, but his words and jokes seem to make people uncomfortable. He does not know how to treat his daughter since he believes that she, like her mother, would just leave him all alone, even though he clearly knows that she never blamed or hated him. Whenever Mao is mentioned, his smile turns into a frown. He is a man who just wants to forget his past and leave it behind to focus on his new life with his new family.
When he is not talking to his new wife and younger daughter, Kaitou is usually seen reading a newspaper while sitting down at the family couch.
Kaitou's hair is parted through the middle with his bangs swept to the sides and his hair stopping a little above his shoulders. When he was younger, the parting at the center of his face was not as prominent, but parted bangs were still swept to the side. Compared to his appearance as a young adult to the present time, not much has changed. In the present time, his face does have a few signs of wrinkles near his eyes, and there are still strands and bits of his hair that stick out. His style usually consists of a button-up shirt with a pair of slacks.
Before the start of the main story, Kaitou was originally married to his childhood friend Yuzuno until he discovered that she had been having an affair with another man. Afterwards he began to spend less and less time at home, avoiding Yuzuno and his daughter Mao in order to spend some time with a woman who would eventually become his second wife. When he comes home and looks at his daughter's face, his thoughts leave him to think that Mao is blaming him for making her mother cry as a result of the sense of guilt that he feels.  As a result of these conflicting feelings, he ends up lashing out at Mao after he divorces his wife and ends up with the custody of Mao.
In a short side story that recounts a time when Mao was still a middle schooler, Kaitou is shown reading a newspaper at the couch in their house. Almost immediately after Mao had greeted her dad, he rises up and tells her that he is going out without looking directly into her eyes. He does leave her some money for her to buy some dinner on her own. 
Kaitou is first shown in flashback of Mao's in which she remembers the time when her parents got a divorce and decided to live with her father because she did not trust the man that her mother was with. During this time, her father practically said nothing the entire time.  After the Nakamura couple are killed in a car accident, Kaitou and his daughter are shown eating noodles together. He explains to Mao that Hiro is the only one who stayed at the Nakamura house to protect it, finding it sad that everyone has gone their separate ways. To Mao, this was the last real conversation that she had with her father. 
In the present time, Kaitou has remarried and appears to treat his younger daughter with a lot of love. When Mao returns home from school, she finds the family gathered at the table, listening to Yui talk about her day. As soon as she announces that she's home, Kaitou's smile disappears.  He responds to Mao's decline to eat dinner by appearing irritated and commenting that she should have called if she had already eaten.  The day after Mao spends the night at the Nakamura house, she calls her house to tell her family that she's coming home that day, apologizing for staying over night without telling them. Over the phone, Kaitou states to Mao that she's always liked staying over there and tells her that she doesn't need to come back.  As soon as Hiro picks up the phone, Kaitou asks if Mao is alright and if it would be alright for Mao to stay with him for a while, explaining that he would help pay the rent.  Later that night, he comes with Mao after she comes back to pack some clothes to drop her off at Hiro's house, handing Hiro the money for that month.
He continues to hand Hiro the money for Mao's living expenses without seeing his daughter.  The next time that he goes to the Nakamura house, he is invited by Hiro to come inside. Kaitou refuses the invitation because he tells Hiro that he wouldn't know what or how to talk to Mao when he saw her. He later suggests that he should instead mail Hiro the money since he explains that Hiro seems to appear angry whenever they meet.  He does comply with Hiro's request to have some time to talk with him by going out for a drink where Hiro tells Kaitou that Mao wants to live him. Despite that, Kaitou wonders if that is really true because he believes that Mao went to live with Hiro simply because she wanted to.  He tells Hiro that since he was able to protect his parents' house all on his own, that he trusts Hiro with the care of his daughter. 
After some time, Mao decides to meet Kaitou at a nearby restaurant to finally tell her father how she really feels. After going through the formalities, Kaitou tells Mao that she doesn't need to worry about the family at home and hands her the expenses for next month.  Subsequently, Mao gains the courage to ask her father if he hates her. In response, he lashes out by saying that both Mao and her mother were the ones who had decided to leave the house all on their own. Before Mao leaves, he tells her to go get a job so that she can pay for her own things. After Mao leaves, Hiro reveals himself from his hiding place and confronts Kaitou, who tries to offer him the rent money that Mao had forgotten, to which Hiro declines.  Hiro states that he believed that Mao had originally been the one who was running away, but now claims that the one who is really running away is Kaitou, leaving Kaitou confused and upset. 
One day, Kaitou ends up dreaming about the past and how his life became the way it was until he wakes up and Oda visits the Motomiya house, not realizing that Mao was not living with her actual family and was instead at the Nakamura house. Opening the door, Kaitou asks what Oda came to their house for, hands him the address where Mao is currently staying at, and then tells him to take good care of her before shutting the door on him before Oda can get the chance to ask him why Mao was not living there.  His wife soon enters the room and exclaims that he called out for Mao in his sleep again.
A few months after summer has ended, Mao visited her home for the first time in a while and tries to approach her father who is busy watching television, seemingly ignoring her and taking his dinner with him to the tv.  Before the family eats dinner, Mao goes up from the table to the couch where her father is at and asks for parental consent for moving into an apartment on her own. Unexpectedly, her father declares that he will not let her live on her own. 
During the dinner for Yui's birthday celebration, Mao tries to say something at the table, but Kaitou still continues to ignore her. Not long after, he snaps back at Mao who gave her sister a gift that she did not like, since the style suited more to Mao's unique tastes and then happily hands his daughter a teddy bear, which Yui appears to love.  While Yui and Mao are making up for some lost time together, Kaitou and his wife are downstairs, talking. When his wife asks Kaitou if he is ready to start talking to Mao again, he doesn't respond, causing his wife to tell him that he just keeps running away. Kaitou continues to say that he's not running away because Mao was the one who left on her own.  He goes on to say that Mao has always loved the Nakamura house and that it would just be for the best if she just stayed there and married Hiro since she's never been happier anywhere else. In response, his wife just looks down at him and asks him if that's how he truly feels. As Mao is about to leave the house to return back to the Nakamura house, Yui comes and drags her father by the hand to say goodbye. Pushed by Yui to say something, Kaitou looks a little perplexed as he grabs his hand and stares elsewhere as he tells Mao that Yui would like to play her again. 
While Mao comes and visits her house again to spend some time with her little sister folding origami, her dad is shown in the same room, on the couch reading a newspaper.  Noticing that even though her dad has allowed her to come and visit, but still hasn't really tried to talk to her, Mao decides to ask her family if they would be interested in going on a trip with Hiro's family. Excited about the trip, both Yui and the stepmother come to the couch where Kaitou is sitting and tell him that they want to go on a trip. Unable to resist the look in Yui's eyes, he says that he may not be able to get some time off from work, eventually relenting in the end.  Somewhat shocked, Mao thanks her dad before he stands up to leave and take a shower. His thoughts are shown, making it evident that he's confused by Mao's behavior and why she was still trying to come back home, thinking that she should be hating him instead. He suspects her of trying to get close to his second wife and younger daughter in an attempt to leave Kaitou all alone again to get back at him. With a hand to his face, he stops himself from continuing to think that way and admits to himself that he doesn't want to think that way, but that he's afraid that he will lose something precious again and that he does not know how to love Mao. 
Sometime later, Kaitou comes back home from work and happily exclaims that he's home until he sees Mao, who has come for another visit, and his smile disappears. At the couch, he comments on how Mao always seems to be upset whenever she comes to visit. When Mao's stepmother explains that something might have happened at the Nakamura house, this only serves to aggravate Kaitou, who is surprised that Mao has gone to their home for help even when she has already chosen the Nakamura house over them. 
At the Christmas celebration in the Motomiya house, Kaito is seen reading a newspaper at the couch while Mao is talking with her younger sister and step-mother. He suddenly stands up and tells Mao to do whatever she wants with his back turned to her after hearing that she doesn't really want anything for Christmas this year except to change the trip from Kyoto to Sendai. Mao's stepmother reassures her by telling Mao that Kaitou has only left because he has to pick up the cake.  At the bakery, he meets Hiro, who has come to pick up a cake as well. He complains that Mao has decided to visit on Christmas of all days. He interrupts Hiro before he has a chance to respond and tells him that Mao has always loved the Nakamura house more, which is something that never changed and then confirms that the location for the trip was changed to Sendai before he leaves. 
During New Years, Mao's family go with Daiki and Hiro to the shrine for New Years.  Hiro thanks Kaitou for coming to join them, to which Kaitou says that it's fine. They all participate in a game called Hana Ichi Monme after gathering in a circle. 
Kaitou comes with his family to meet Mao and the Nakamura family at the station. He asks Hina if she remembers him after telling him that she seems to have grown up into a fine young lady. They walk together, ahead of both Hiro and Mao, who are trying their best to get a chance to become closer with their respective family members.  During the trip, Mao asks him if he likes Masamune, and he gives her a simple reply, saying that he doesn't particularly like him, causing another awkward silence between the two of them. He is later shown eating a meal with his second wife and younger daughter Yui along with Hina, while Hiro, Daiki, and Mao ate at a separate table.  Hiro thanks Kaitou for coming, and he tells Hiro in annoyed tone that Hiro doesn't have to keep thanking Hiro for everything. Instead, he changes the subject and asks if Hina has gone back home yet telling Hiro that they must be similar in that both Hina and Mao hate Hiro and himself respectively, causing Hiro to tell Kaitou that . He teases Hiro by asking if he has a thing for Mao, and does not reply to Hiro after he tells him that Mao and Hina are quite alike. 
The next morning, Kaitou is told by his wife that he should talk to Mao because she seems upset over the fact that Hina thinks that she is responsible for the death of her parents. As he looks over to where she is sitting, he realizes that Hina must have thought of herself as the one responsible for her parents' death in order to prevent her sadness from getting to her. He acknowledges the fact that he understands her way of thinking because he loathes himself in the same way and admits that she is a mirror reflection of himself. Sitting next to her, he starts a conversation with her and wonders why she doesn't want to look at the souvenirs until she tells him that it's because she lives in the area. Exclaiming that it doesn't seem like such a fun vacation when you're still in your local area, Hina tells him that she only wanted to see Daiki and Hiro again. This makes Kaitou ask Hina why she didn't just go back to the house and answers his own question when he states that she refuses to go back to the house because her parents are dead. He tells her that she doesn't have to blame herself for their deaths and that they loved her very much. He explains that he noticed how her house was almost always bright and how sickening it was that Mao spent so much time there. He does admit that her frequent invitations may have allowed Mao to turn "all right" in spite of everything that's happened to her.  He reveals to Hina that he had somehow hoped that in possibly saving Hina, that he could somehow redeem himself for his past mistakes. He finally admits to her and to himself that he still cannot face Mao and that he still continues to run away. About to head up to the gift shop for some souvenirs, Kaitou tells Hina that the "Hi" in Hina's name represented the sun. He shares the fact that his parents had told him that she was always so bright and cheerful.  This causes Hina to open up her heart and feelings, showing all the pain and suffering that she's kept inside for so long and bursting into tears. Kaitou turns around while Hiro comes up to Hina with a worried look on his face. From his back, Mao feels that her dad was crying for a second as well. 
Once Hina honestly tells her brothers how she feels, Mao's stepmother suggests that the Nakamuras go visit their relatives while the Motomiya family do some sightseeing of their own. Grabbing Kaitou's and Mao's arms, they go outside. In the taxi, Kaitou and Mao sit on opposite sides of the car with Yui in between them. They meet each other eyes in the car before Kaitou turns his head away.  Kaitou ends up alone with Mao when Yui drags her mother through the festival to get some cotton candy. Even though Mao tries to catch up with the two of them, he tells her that they can just call them later.  Passing through the stalls, Mao notices a prize that she wants to get and tries to play this shooting game to win it. Noticing how bad Mao is, Kaitou takes the gun from her and shows her how to shoot properly, winning the prize and giving it to Mao.  Wanting to do more things with her father, Mao tells him that she wants to go goldfish scooping next. He tells her that they cannot keep the goldfish, but finally gives in. The first time that Kaitou tries to scoop up fish, he ends up breaking the scoop and gets told that it's over for him by a little kid. He gets a second scoop and also accidentally breaks the scoop for a second time. After Mao shows him how to scoop goldfish properly, Kaitou is able to catch a goldfish, excitely calling Mao by her name. This results in another awkward silence between the two of them.  He calls his wife and the two of them decided to wait for the other two since Yui also wants to scoop goldfish.