Kou Yukina (雪名 皇, Yukina Kou) is a main character in the Sekai-ichi Hatsukoi series. He is in a relationship with Shouta Kisa.
Kou has light brown hair with matching colored eyes, along with various piercings in his ears; four piercings on his left ear and one on his right. When working at Marimo Books, he wears the standard uniform, which consists of a white collar long sleeve shirt, regular pants and a blue apron designed with charms and a name tag.
Outside of work, he is usually seen wearing a solid-colored, long-sleeved shirt and a beanie hat. Kou's main jacket is a long green overcoat with a fur-lined hood. When he is painting in his university, he wears a one-piece jump suit that is heavily stained in dry paint due to the messy activity. When Kou is home or cooking, he ties his hair into a ponytail and wears barrette clips to hold his hair back.
Kisa is Kou's current lover. They both met in Marimo Books when Kisa had Kou as his cashier and became attracted to him due to his handsome looks. When Kisa began regularly visiting the store to watch him from afar, Kou had been aware of it the entire time and simply figured that Kisa was a high school boy with a crush on him. Kou admitted how he didn't find the action at all odd or strange, given that quite a few girls did the same thing. It wasn't until after Yokozawa came to talk to the manager that they were finally formally introduced.
After work, Kou went to a cafe and found Kisa sitting by himself in the corner. He went over to greet him and they fall into a discussion about the books he edited - getting to know each other better. As the conversation carries, Kou learns that Kisa wasn't as young as he originally thought, shocking him given Kisa's young looks. When their conversation shifts over to the books that Kisa has edited, Kou decides to build a display to help promote the book. As Kou draws up the rough sketch, he notices that Kisa has gone quiet. As he looks at him, Kou takes note of Kisa's cute face and "loses control". He stands up and, using the note pad he was drawing on to hide them from sight, kisses a stunned Kisa.
The next day, when he is leaving work, he notices that Kisa and a man he saw a few days prior arguing outside the store. He manages to scare the guy away and, after this, they head to Kou's house where Kou finds out that Kisa edits his favorite manga. He then confesses his feeling for Kisa, also revealing that he's been aware of his regular trips to the store to simply watch him, much to Kisa's embarrassment. After some brief time, Kisa decides to give Kou a chance and they enter a relationship.
The two's main obstacles often root from Kisa's deep insecurity, especially in regards to their age difference and Kou's popularity - knowing how he could easily have any person he wants. However, Kou always declares his love to be for Kisa and assures him that it is him that he wants regardless of anything else the world has to offer him. While Kisa at times still doubts Kou's love for him, Kou has shown to be very passionate about Kisa. He absolutely hates the idea of Kou having a possible attraction towards anyone else or the other way around, sometimes showing a jealous side, loving him dearly.
His love is strongly demonstrated when Kisa breaks up with him over the phone following a misunderstanding. Intent on clearing things up between them, he went straight to Kisa's apartment following the phone call to demand an answer from him. When he instead catches Kisa on the verge of kissing Ichimura, he yells Kisa's name in a clear fury before going up and angrily slapping him. Once alone inside the apartment, he reveals how he always understood Kisa's intense work schedule and didn't want to be a burden by asking more of him after he would come home from work always exhausted. He admits that he does deeply wish to spend time together, but he wants to think of Kisa's personal time and energy first.
However, Kisa still insisted on a break up since he believed that they were basically strangers and didn't know much about each other. In response, Kou becomes passionate in an immediate refusal to accept a break up without a good reason. He then learns about Kisa's deep insecurities about him finding someone "young, beautiful and cute" and leaving him behind and their lack of knowledge about each other. Kou answers to this that he will pick the person he wants as a romantic partner before he spouts off various random details about himself to help Kisa know about him better.
He admits that, while he knows that Kisa slept around a lot in the past, as long as Kisa "only looks at [him]" from there on out then he is accepting of it. (However, in the manga, Kisa's promiscuous history is shown to bother Kou to a considerable degree. But he does try to reasonably handle it.) They make up after this, with Kisa attempting to feel more confident about himself and their relationship.
Rio Kojima is one of Kou's closest friends from the university. She is apart of the fashion department and has blackmailed Kou into modeling for her during a school festival on one occasion. She helped Kou learn how to cook, which lead to Kou making meals for Kisa. It isn't known whether Rio is aware of Kou's relationship with Kisa or that she is the reason Kisa and Kou have had rough patches in their relationship.
Since the two are clearly close, Kisa frequently finds himself jealous over Rio's friendship with Kou. However, Kou insists that they are strictly platonic. In the Manga, he reveals that the two had once tried dating, but it ended in a mutual break up and opted for a simple but strong friendship. This appears to not hinder their friendship whatsoever.
- He is a fourth-year university student, studying in Touto University For Arts, and majors in oil painting.
- He likes all kinds of food.
- His good points are that he is proactive and optimistic, but his weak points are that he is very stubborn.
- Kou's favorite artists are Klimt (known for The Kiss),Vermeer (known for Girl With The Pearl Earring) , Sargent (known for Portrait of Madame X), Hammershøi (known for Ida Reading A Letter), and Waterhouse (known for The Lady of Shalott).
- His hobbies include drawing, reading and visiting museums.
- He has an older brother who is currently unnamed and has only been mentioned once in the anime, but twice in the manga.
- His zodiac sign is Virgo.
- His blood type is A.
- He is originally from Sapporo, Hokkaido.
- His shoe size is 27.5 cm.
- His pairing with Kisa is referred to "Erotica" by the fans, referring to their beliefs of them doing very erotic things and them being erotic as well.
- He is very popular among girls. Due to being aware of his influence on girls, he uses this as a tactic to sell his favorite manga series with relative ease.
- He has told Kisa's brother that he doesn't flirt with girls intentionally, which isn't true since he uses flirting as an effective tactic to sell books ,it may have implied he had a promiscuous past although it was never revealed.