|Kanji|| 相原 琴子|
|Rōmaji|| Aihara Kotoko|
|Also known as|| Kotoko-chan|
|Age||17 - 26|
|Occupation|| High School Student (former)|
University Student (former)
|Affiliation|| Tonan High School|
|Relatives|| Naoki Irie (husband)|
Kotomi Irie (daughter)
Shigeo Aihara (father)
Etsuko Aihara (mother)
Shigeki Irie (father-in-law)
Noriko Irie (mother-in-law)
Yuuki Irie (brother-in-law)
Kotoko Irie (入江 琴子Irie Kotoko), née Aihara (相原, Aihara), is the main female protagonist of the Itazura na Kiss series who is in love with the handsome and intelligent Naoki Irie. After her newly constructed house collapsed, she moved into the Irie household as her father being a very close friend of Naoki's father, Shigeki Irie.
Kotoko is a cute and adorable slim girl with long red-brown hair with bangs, big warm brown eyes, a cute upturned nose and a smile on her face. Throughout the series, she has many different outfits and hairstyles, but usually either leaves her hair down, or has it in pigtails or braids. When she wears her nurse uniform, she normally has it in pigtails to keep it short and out of the way of her work.
Kotoko is an absent-minded, cheerful, romantic and emotional girl who is rather clumsy but she is very determined and driven. Even though she has a lot of spunk and can be very feisty, she is a little stupid but can be very lovable. She shows her emotional side whenever she would see Naoki Irie with another girl, like Christine Robbins, but this just displays her love for him. Kotoko is regarded as being stupid and known for messing things up. She is also a comedic character from what Naoki had said. She is continuously described as quite dense in matters associated with love, but is very persistent and works hard for things she wants.
Kotoko has lived with her father ever since her mother died when she was at a very young age. After she enrolled into Tonan High School, she was placed into Class F (classes are arranged by letter) along with her friends Jinko Komori, Satomi Ishikawa and Kinnosuke Ikezawa, also known as "Kin-chan". During the freshman speech on the first day of school, she overheard some girls talking about Naoki Irie, who was to deliver the speech. Hearing that he was possibly the number one genius in Japan, Kotoko imagined a studious person. However, when Naoki Irie appeared and began speaking, she was surprised at how different he looked and instantly fell in love with him.
For the next two years, she tried to win his affections by studying hard to get into Class A while working up the courage to confess her feelings. During the end of her second year (still in Class F), she was able to write a love letter, but before she could give it to him, Naoki had already rejected it. She then proceeded to move into Naoki's house after her house is destroyed by a earthquake. Her father is old friends with Naoki's father, which is how this came to be.
- Main article: Kotoko Aihara/Relationships
Kotoko has always liked Irie-kun, and one day tries to give him a love letter expressing how she feels about him. But sadly he does not accept it. Later Kotoko's house collapses because of bad construction and an earthquake. So she and her father go and stay at her fathers friend's house, and their eldest son just so happens to be Irie-kun. So now Kotoko must live in the same house as her crush, and through this her love for Irie-kun grows stronger. Soon after Irie-kun realizes he also has feelings for Kotoko and confesses to her in episode 14. In that same episode Irie-kun proposes to Kotoko and they get married. Kotoko and Irie-kun have their hard times, but they always stay strong in the end. At the end of the anime they have a child named Kotomi Irie.
Just before her marriage to Naoki, she had a brief romance with Kinnosuke Ikezawa, a friend who liked her since freshman year. She honestly knew she didn't love him, but hoped she could learn to, since an arranged marriage had been prepared for Naoki.
- It Started with a Kiss / They Kiss Again: Yuan Xiang Qin (袁湘琴 Yuán Xiāng Qín)
- Cowok Impian: Arika
- Playful Kiss: Oh Ha-ni (오하니 Oh Ha Ni)
- Kiss Me: Taliw (ตะหลิว Tah̄liw)
- Miss In Kiss: Xiang Yue Qin (向月琴 Xiāng Yue Qín )
- Kotoko had a crush on Naoki since her freshmen year.
- She's bad at cooking, despite her father being a famous chef in Tokyo.
- She falls down steps a lot.
- She often gets jealous when she sees other girls talking to Naoki.
- Kotoko has only been angry enough to say that she doesn't like Naoki two times despite what he's said. First when Irie takes her into the alley way after she showed everybody his picture as a girl at the restaurant and second when Naoki slaps her.
- Kotoko cannot speak English well.
- Most of the boys in the series seem to fall in love with her, but that doesn't change her feelings for Naoki.
- Even after marriage, she regards Naoki as "Irie-kun".