Ritsu Onodera (小野寺律, Onodera Ritsu) is one of the main characters in Sekai-ichi Hatsukoi. He is in an unofficial relationship with Masamune Takano.
Ritsu has light brown hair and long bangs that frame the sides of his face. He has wide, green eyes and fair skin. When he was 15, his hair was styled differently with his bangs parting in the middle. His hair is said to be silky in texture (to the point where one of his close female co-workers complains during a drunken rant about how much she envies it).
He is described by Yoshino as being very attractive and having a "vogue body type", with high hips and a small face with perfect features. Ritsu doesn't like smiling for a long time though it's often required during company parties, stating how it makes his jaws hurt. Like most male characters in the series, Ritsu is relatively tall - being slightly taller than average height. However, like most of the couples of the series, he is significantly shorter than his lover, Masamune.
The first meeting between Masamune (Saga at that time) and Ritsu was during high school when Ritsu was attempting to grab a book on a shelf that was far above his capable reach. Seeing Ritsu's difficulty, Masamune reached out and pulled the book out for him. Ritsu thanked him and walked away before turning back to look at him.
After their first meeting, Ritsu slowly fell in love with Masamune. Like most people, before this first meeting, Ritsu didn't believe in love at first sight. However, following this meeting with Masamune, his feelings quickly changed. Even so, the name of the unknown senpai remained a mystery to Onodera, thus leading him to search through the books that Masamune would often borrow so he could see the book record cards. Despite feeling fairly creepy about his actions, searching the record cards allows him to learn the name of his first love. Following this, Ritsu further realizes that his actions are borderline that of being a stalker. This being since he had borrowed almost all of the books Saga had checked out, regardless of what genre the book was, and frequently watched him from afar usually behind a corner or bookshelf where he couldn't be seen.
Three years later, they meet again in a similar situation. This time, Ritsu was reaching for a book that happened to be the same one that Masamune wanted as well. Their hands touch, causing Ritsu to blush and call out Masamune's first name in surprise. Masamune then asks how Ritsu knew his name. In the midst of the sudden confrontation, Ritsu impulsively confesses his love for Masamune without thinking. To Ritsu's surprise, Masamune doesn't mind Ritsu's confession to him and even says that he wouldn't mind going out with him. Ritsu instantly thinks that the offer is a joke, but Masamune says that it wasn't.
Days later, after school- an extremely nervous Ritsu and Masamune walk to Masamune's home. Ritsu enters the house to see a cat that Masamune saved on a rainy day, he then continues on to Masamune's room without commenting on it. While Ritsu waited for Masamune, he sees Masamune's bed and, as it was his dear wish from the day he had met Saga, he wanted to be on the bed of his first love. On a sudden whim, he throws himself on the bed, but then scrambles back to the floor, thoroughly embarrassed.
A few seconds later, Masamune walks in with tea and offers that they watch TV together. While they watch a television program together, Ritsu mentions the cat at the doorstep. Masamune remembers the day when he rescued the cat and chuckles. Masamune jokingly tells Ritsu that he had also been stalked and Ritsu instantly gives Masamune a very formal apology, but Masamune tells him that he didn't mind. He then leans forward in an attempt to kiss Ritsu. Shocked, Ritsu pushes him away. However, after a moment, he allows Masamune to kiss him. After sharing a second kiss, Masamune hugs him and asks to sleep with him . Ritsu, momentarily stunned, replies with a yes, During their first time, Masamune whispers that he loves Ritsu, using Ritsu's first name for the first time (Ritsu finds it normal, even though he never told him his name...). Ritsu and Masamume then share a passionate kiss.
Sadly, their romance comes to a rather tragic end when Ritsu asks Masamune if the two of them were going out and Masamune laughed nervously in response. However, Ritsu fell under the belief that the laugh meant that Masamune was joking about the whole thing. Ritsu, heartbroken, kicks Masamune some day afterwards in anger and quickly leaves Japan to study abroad in England. Masamume, unaware of what Ritsu believed about him, became heartbroken about Ritsu seemingly leaving him for no reason and appeared to have only used him.
A few years later, he returns to Japan to work at his father's publishing company. When seeing his co-workers believed that his success was solely based on him having family connections, Ritsu decided to leave his father's company to work in literature to prove that he can make it on his own without his father's name. Thus setting up the events for Sekai-ichi Hatsukoi.
After a few concerns with his old job (due to his colleagues belief that he was 'riding his parents coattails' in the company), Ritsu decides change work to a literature department at Marukawa Publishing. Due to what appeared to be a mistake in his employment contract, he becomes assigned to work on Shoujo manga (girl comics) which disappoints him since he had never done anything other than literature and had no interest in Shoujo manga. He is also upset because he knows very little about editing manga. He pleads with General Affairs to try to re-assign him to the literature department to no avail.
After meeting his boss, Takano Masamune, he wants to tell Masamune that he wants to quit due to little knowledge in such a department and field work. However, he decides to continue with manga and give it his best after being called 'useless' in the job by Masamune, much to his anger. Ritsu later finds out that his father had him placed in the Shoujo manga department instead of literature during his transfer to the company, deliberately having him switched for unknown reasons. Ritsu later decides to stay and work with Shoujo manga so he can gain success and prove to others that he is not riding on his parents' coattails and can be a great manga editor based on his own personal skills and hard work. Ritsu usually tells himself that he will quit working at Marukawa as many of the workers like to pick on him for being a "newbie", or that he frequently butts heads with Takano.
Masamune is Ritsu's current boss, neighbor and first love in high school. In the manga, Masamune and Ritsu have been neighbors for at least a year. However, they had never met or ran into each other due to irregular times leaving and arriving back home while Ritsu was still working at his father's company. In the anime, when Ritsu moves into his new apartment because he wished to start completely fresh in life alongside his new job, he finds out that Masamune is his neighbor. This detail shocks him, even leading him to briefly switching apartments somewhere else, but not seeing the point in such trouble.
Ten years prior to the storyline, after Ritsu went off to study abroad, Masamune attempted to find him, but was never able to do so due to knowing Ritsu under a false name. Ten years passed and Ritsu ends up working at Marukawa Shoten's Emerald department where Masamune is his boss. Neither of them realize who the other is because, due to his parent's divorce, Takano's last name had been changed and Ritsu had been using his actual name which Takano didn't know. Also, since ten years had passed, two naturally looked different than they had in high school. Takano had changed his hairstyle, and the previously shy Ritsu had a more confident, combative demeanor. After finding out that his new boss is his former lover, he adamantly assures Takano that he will never have such feelings for him again, although Takano vows that he will make him fall in love with him again.
While Takano clearly still has feelings for Ritsu and openly refuses to give up on him, Ritsu often betrays his deeper feelings of loving Takano through constantly denying them. After a few words with Takano while waiting for the rain to lighten up, Takano says that he had tried to find him when they were in high school. Ritsu was touched by the admission, although he was still embarrassed about how he had given a false name to his first love in high school. A combination of his feelings and the events leading up to this cause Ritsu's feelings for Masamune to overflow such as they did in high school. It was here beneath the overhang that Ritsu finally confessed 'I love you' to Takano. However, Takano was unable to hear him due to a sudden downpour of rain that drowned out his voice. Although he had a feeling that he missed something very important, Takano is unable to get Ritsu to repeat himself.
Though Ritsu acts like he hates Takano's advances, he deeply cares for him, even if he has yet to admit it. He often makes this apparent when he becomes worried about his health. For example, after Takano catches a cold, he rushes to buy him medicine and attempts to cook for him.
His continued love for Takano is often shown when he becomes jealous of Takano's possible romantic relationships with other people, such as with Yokozawa. One time, he had even begged him not to go visit Yokozawa at night and even implies that he still cares for Takano in a romantic sense just to get him to stay, one of his closest moments to a love confession. While Ritsu has admitted that he "has someone [he] loves", he has yet to actually say "I love you" to Takano.
Ritsu and his mom have somewhat cold and distant relationship. She arranged an engagement between Ritsu and his childhood friend An despite his protests that he didn't wish for a marriage, Despite knowing her son's feelings, she often nags him to spend more time with An, often resulting in Ritsu refusing and claiming that he has work to do first.
After Ritsu repeatedly refuses to accept the marriage, she asks Ritsu if he already has someone he loves. Ritsu is unable to give her a clear answer. When An later cancels the engagement herself, with the excuse that she can never love Ritsu as her husband, she calls Ritsu in a fury. She angrily demands to know why An would cancel the engagement, resulting in Ritsu hanging up on her. Ritsu usually tries to avoid her calls or personal contact with her.
An is Ritsu's ex-fiancé and friend since childhood. She comes to Ritsu's apartment late at night to greet him after coming back from Paris, having waited until her cheeks were red from the cold, and gives him souvenirs. While taking the gifts, he brings her to a taxi. Takano confronts him about his relationship with the young woman. To this, Ritsu ends up telling him that An confessed her feelings to him years ago, but he turned her down because he loves someone else. He claims that he only held her hand, but nothing else had happened between them.
Later on, she appears at the Teito Hotel for a party, while Ritsu is working there as well for the Marukawa New Years Party. She confesses to him once again, but Ritsu turns her down again. This brings An to ask if he might be in love with "the person from high school", to which he admits may be correct. A couple months later, Ritsu gets a call from An, explaining that his mother was sent to the hospital. Meeting An, the two comfort each other and he takes her home. She later deduces that Ritsu has feelings for "Mr. Next-Door-Neighbor" when observing his behavior around him, later remarking how Ritsu makes "that face" with Takano and no one else.
After this, she confronts Ritsu about her theory. While he initially tries to deny it, he admits to his feelings and asks if she believes his romantic feelings for another man to be wrong. She says that she doesn't believe she is in any position to judge him and simply wishes for him to be happy - also telling him about "the face" he only makes with Takano. She urges him to accept his feelings for Takano so that he can finally find personal happiness, but warns him to make sure that his feelings are not half-hearted to avoid further heartbreak.
When seeing Takano watching them nearby, she demands that he better not hurt Ritsu - vowing that she will never forgive him if he does. After declaring this, she runs away from the scene. Later on, Ritsu receives a furious phone call from his mother. His mother then angrily tells him that An canceled their marriage arrangement with the excuse that, while she loves Ritsu, she cannot love him as a husband.
For a majority of the series, Ritsu has a relatively poor and bad relationship with Takafumi. This is due to how Takafumi had strongly believed that Ritsu was the sole source of Takano's pain in high school and college.
As a result, he often dismissed his work proposals and often made the two's working relationship very hard and difficult. This went on until Takano confronted him about sabotaging Ritsu's working assignments. When Takafumi and Ritsu would see each other (often unexpectedly), Takafumi would get verbally aggressive and intimidating with Ritsu. He would always demand that Ritsu stay away from Takano, especially when it became clear that Takano was pursuing Ritsu romantically again. He also held a grudge towards Ritsu because he himself was in love with Takano, viewing him as a rival for Takano's love and affection.
Soon, Takano tells Takafumi that despite the years and past pain, he is still in love with Ritsu - not him. Takafumi painfully accepts this and stops acting as aggressively towards Ritsu as he did before. When the two meet one early morning before work, the two talk together. This ends with Takafumi only requesting to know one thing - this being if Ritsu truly loves Takano. After a moment, Ritsu admits that he does. Takafumi accepts this and the two finally begin a less aggressive relationship at work together. Takafumi even admits that Ritsu does a good job with his field work and to keep it up.
However, he is still very protective of Takano and makes this clear to Ritsu. He warns him that if he ever hurts Takano again, he would not hesitate to take Takano back. (Although the light novels prove this to be a false threat due to Takafumi's newfound relationship with Kirishima.) While their relationship is still somewhat difficult, Takafumi has a better level of respect towards him than before. In the manga, he even genuinely inquires as to how Ritsu's relationship with Takano is going. When learning of the two's troubles, he snaps at Ritsu to stop playing around with Takano and to be more serious about the relationship.
- He only does dishes and laundry when the one he uses gets dirty.
- It is also mentioned that he was one of Ryouichi Sumi's (father of Keichi Sumi, friend of Misaki Takashi also from Junjou Romantica) editors at his previous job.
- Ritsu's shoe size is 26.5.
- It is later revealed that Ritsu owns an iPhone 4. It is currently installed to be used and typed in hiragana and katakana. It has been used when Ritsu was texting An Kohinata an apology via text; telling her that he is coming home from the station.
- His favorite food is dorayaki.
- He is a terrible cook. In the manga, he is amazed with and loves Takano's homecooked meals, surprising Takano given that they are basic kitchen meals.
- His current hairstyle resembles the one Takano used to have during high school.
- His pairing with Takano is referred to as "Nostalgia," referring to their past relationship and their rekindled feelings.
- In the manga, Ritsu admits that he lost his virginity to Takano. This being during their high school relationship.
- His and Takano's relationship counterpart from the mangaka's other manga "Junjou Romantica" is the Junjou Romantica pairing of Usami and Misaki; mainly due to them being the first pairing introduced, the pairing that takes the longest to confirm they are lovers, and the pairings with the most overall exposure in both the anime and manga.
- Until he dated Takano in high school, Ritsu never ate fast food or any kind of instant food. He also cannot handle giving his order, failing at it in high school and just as so in his adult years.
- Following his break up with Takano in high school, Ritsu dated a few girls. However, these relationships were significantly brief, never lasting long. (Ritsu's longtime friend An, during a confrontation about Ritsu's true feelings, also confirmed this.)
- When transferring to Marukawa Publishing, he had requested to be put into the literature department. However, his father intervened and instead had him deliberately put into the shojo department, much to Ritsu's confusion when he found out about this detail. Why his father instructed that Ritsu be assigned to the shojo manga field instead of literature is left unknown and hasn't been re-explored in the manga.
- Ritsu's favorite subject back to high school was English.
- Ritsu used to read all the books at school. And also in the beginning of his job at shojo department.