A naive high school student determined to enter the university that his brother was unable to after the death of their parents. This leads to him being tutored by his brother's friend, Akihiko, which ends up shaking up his life considerably.
The Heart / Team Mom: He is very obsessive about being attentive and caring for people around him, and he doesn't want to be a burden to anyone.
Broken Messiah: His default mode is being Tsundere to Akihiko and his usual brash, childish and idiotic personality. Not to mention anything concerning about Akihiko also can result him into becoming this, too.
Distressed Dude: In the second season where Misaki was curious of Akihiko's past so he willingly being kidnapped by Haruhiko. He barely managed to subvert this trope by escaping through the window at the cost of spraining his leg, seconds later being held in a Bridal Carry in Akihiko's arms.
Taken Up to Eleven when you saw his feminine traits such as his housewife role, his first name is actually a unisex(Misaki is both male and female name) name, and his family thought that he would be born as a girl. At least he uses Ore though.
Dude Magnet: He at some points wonders whether he is producing some kind of pheromone that attracts guys.
He also believes that he posses a pheromone named "Usamone", as he easily attracts and befriends the members of the Usami Clan.
Breaking the Fourth Wall: In Junjou Romantica act 17 as he was unwittingly jealous with Mizuki who were apparently flirting around Akihiko and bullies him, he regret that he has wasted so many times on thinking whether Mizuki had a thing on Akihiko.
Misaki:(thinking) But what I find even more unsettling... is that I've just wasted four pages straight worrying about this drabble!!! Makes me sick, I tell you!
House Wife: Not literally but he's self-effacing, caring and friendly to everyone, good at housekeeping, etc. He'd be a perfect example of the trope if it weren't for his Tsundere streak when up against Akihiko.
Hyper Awareness: Even though he barely knew Akihiko in the beginning, he was able to understand the latter's true feelings and cried due to sympathizing in him after Takahiro introduced his bride to Akihiko.
Justified that he is very attentive towards others around him.
It's All About Me: All of the problems that he needs to deal with the Usami Clan are completely centered about him.
It's All My Fault: He still blames himself for the death of his parents, to the point that he will never tell anyone about his parents' death anymore since he will always get the same answer - "It's not your fault."
Heck, he has a habit of blaming himself over everything, especially if something goes wrong.
Love Epiphany: For a long time, he doubts whether or not he is in love with Akihiko, and finally admitted it in Volume 8. He already had his Love Epiphany some time before that, though. He was just too stubborn to admit it.
Oblivious to Love: He's very naive when it comes to love, which makes him prone to be denial about his feelings to Akihiko.
Older than They Look: He doesn't look like an adult at all and still looks like a teenage boy, despite that he is currently 22 years old.
Only Sane Man: He declared at some times that he keeps meeting weird people everywhere he goes. At some times, he manages to invert this trope by being the center of attention and surprise of everyone.
Probably the most kind-hearted example of this trope.
Wild Mass Guessing: YMMV, but fans had a lot of headscratches about whether he is truly in love with Akihiko, whether he has been accepting the fact that he's in love with him and the reasons for his denial and oblivious attitude about his feelings.
Usami "Usagi" Akihiko
"You’re mine for the rest of your life. Give up."
Voiced by: Hikaru Hanada
Famous author and member of an extremely wealthy and dysfunctional family, he harboured feelings for his friend Takahiro Takahashi for a long time, and took on tutoring his younger brother Misaki as a favour. He ends up falling for him instead.
He also couldn't keep a cool head when somebody woke him from sleeping, either.
Bridal Carry: He carried Misaki like this the most often compared to the other pairings that Nakamura had created, as this happens twice so far in the manga and sometimes in the covers and the official images.
Cloud Cuckoolander: Buys every type of marimo in the trip to Hokkaido. Also the strawberry and cherry incidents show that he is not altogether of this world.
Cock Fight: Narrowly averted. When he learned about his half-brother's intentions of taking Misaki for himself, hadn't Misaki held him back, he clearly had the intention to go and reality-check Haruhiko with a good punch in the face.
While they usually prefer Snark-to-Snark Combat, Usagi has ended up slamming Ijuuin into a wall one time and it may have very well escalated past that.
Deadpan Snarker: He always becomes this to Misaki due to his arrogant personality.
Hidden Heart of Gold: For all his pervy and possessive behaviours towards Misaki, his general idiosyncrasies, and his utter lack of social skills, more than one character has commented on his kindness. He is also willing to go through great lengths for the sake of people he cares about, especially about Misaki.
Childhood friend of Akihiko, Hiroki ended up heartbroken when he realized Akihiko would never return his feelings. Fortunately at that moment, Nowaki showed up to sweep him away like a typhoon. He eventually becomes an associate literature professor at Misaki's school, and works under Miyagi.
Bookworm: Is one ever since his childhood (he was willing to look up the words he didn't know even if that lead to even more new words). He has such an extensive collection that books pile up higher than he is in his apartment and Akihiko borrows reference materials from him.
Pride: There is a reason his story is called "Egoist"
Sadist Teacher: He walks the line between a humourous version of this and the Stern Teacher. He genuinely believes he is being fair and simply has high expectations of the students. On the other hand, he throws chalk and books at them for texting or talking during class, which would probably get him assault charges in real life. They call him "the demon" for a reason.
Sex Equals Love: He failed out on this one harshly when he slept with Akihiko hoping it would convey his feelings and that Akihiko would love him back. It really didn't. Further zigzagged in regards to his argument that he only sleeps with people he loves, as there are implications that he didn't in the past, and Akihiko and Nowaki are more the exceptions than the rule.
Snark Knight: Has quite snappy conversations with Akihiko and Miyagi
Throw the Book at Them: Nowaki being his most frequent victim, at least at the beginning of their relationship.
Nowaki, found orphaned on the day of a typhoon, started working out of junior high but is determined to enter university. He falls in Love at First Sight with Hiroki and begs him to be his tutor in order to spend time with him. Eventually he realizes both his goals and becomes a pediatrician.
An accomplished but somewhat listless literature professor at M. university who is Hiroki's senior. Some time after his wife leaves him following her affair with another man, her little brother shows up in his life demanding that he "take responsibility" because he loves him.
Bunny-Ears Lawyer: It's hard to believe that he is a prominent figure among literary researchers at first since he hardly works on screen. Hiroki has commented on this.
His Story Repeats Itself: Miyagi's situation with Shinobu mirrors his story with his teacher in the past, with him switching roles. He is interested in literature because of his teacher, thus becoming her Spear Counterpart.
Karma Houdini: During the time when Hiroki and Nowaki were having serious problems, Miyagi intercepts a message Nowaki wants to leave for Hiroki to tell him he's going to be late meeting him. Miyagi never passes along this message, and by doing this Hiroki suffers a massive Heroic BSOD and his relationship with Nowaki is almost fractured beyond repair. Yet this isn't ever brought up again, and Hiroki and Nowaki have no idea he did this.
On his way to his sister's wedding, he is attacked by punks until Miyagi comes to his rescue. Shinobu thinks it's destiny and they are meant to be together until he finds out that Miyagi is his sister's fiance. When they get divorced he comes back to Japan because that must be destiny.
Hot-Blooded: When he isn't snarking at everything, he's usually yelling.
Insane Troll Logic: Borders on this with regard to why Miyagi should be in a relationship with him.
Insufferable Genius: he is supremely confident that he will get into the best university in Japan... And he's right. That said, though, he seems to continuously hold the Idiot Ball when it comes to relationships. So, in other words, he's very similar to Usagi.
Just Ignore It/Somebody Else's Problem:He thinks that the problem of their 17-year age gap is basically nonexistent, and he doesn't care one bit that he's the son of Miyagi's boss! He also thinks the fact that Miyagi is concerned about any of this is stupid. Miyagi has a very different opinion.
Lethal Chef: Besides making cabbages, he can't cook anything else. And he is still working on cooking those competently.
The son of a wealthy family that runs a publishing business, which he only entered because he had a knack for it and couldn't hack it as a writer. Crosses into the Romantica storyline as another editor of Akihiko's, and was the person who convinced him to publish as a teenager.
Brilliant, but Lazy: He still gets his work done, but very few people alive have ever seen that process occur.
Bunny-Ears Lawyer: Seen more in Sekai-ichi Hatsukoi than Junjou, but he has some really strange and frustrating...er, "quirks" that constantly leave his staff in a state of heightened irritability. Unfortunately he is just that good, so he's not going anywhere.
Living Emotional Crutch: Towards the end of the Mistake storyline he proves the reason he keeps Asahina around isn't because he can't take care of himself, but because he is emotionally dependent on him.
As his family was about to commit suicide together due to bankruptcy, Isaka's father found them and hired them, leading to Asahina becoming playmate to Isaka and eventually a sort of caretaker. His gratefulness to Isaka's father leads to Isaka misunderstanding just who he has feelings for.
Beware the Nice Ones: A kind, welcoming and beautiful woman...who hides a fierce streak that is especially visible when Akihiko doesn't respect his deadlines.
Fag Hag: With the added benefit of being genuinely attractive, somewhat intelligent and very supportive of Akihiko's relationship with Misaki, which makes for a refreshing positive portrayal of this character type.
Not Blood Siblings: He and Akihiko have different mothers. His mother was their father's lover.
Missing Mom: He was taken into the Usami family when he was in junior high school after his mother's death.
Not So Different: After talking with him, Misaki believes despite how different they look or how much they may dislike one another, the Usami brothers actually have a lot more in common than they think.
Sugar and Ice Personality: He seems like he has no emotions whatsoever, but later chapters reveal that he may actually be in love with Misaki, and is willing to do anything to make sure that Misaki is happy.
Father of Akihiko and Haruhiko. Married into the Usami family.
Bitch in Sheep's Clothing: Despite being all smiles, he went from constantly trying to guilt Misaki into leaving Akihiko, to outright telling him his existence is a hindrance then getting him to doubt his self-worth.
Papa Wolf: It's obvious he cares very much for his sons and tries to do whatever he can to keep them from being hurt. However, he can be a real Jerk Ass about it. When he learns Haruhiko has feelings for Misaki, he tricks Kaoruko into coming back to Japan so the two could be engaged and; despite knowing Akihiko's feelings for Misaki (and being told to stay out of his business), Fuyuhiko still brings match-making photos for brides. His excuse? He knows what's best.
Foil: To Akihiko. Akihiko has light hair and eyes, and typically wears suits while Ijuuin has dark hair and eyes, and dresses casually (the one time we do see him in a suit, even his suit is opposite). Unlike with Akihiko, Misaki reads Ijuuin's works and has no problem openly declaring his "love" for him.
He Cleans Up Nicely: Looks like an absolute wreck whenever the deadlines for his manga are near (think the Emerald guys from Sekai-ichi Hatsukoi during the last days of their cycle), but is actually very, very handsome.