Tonari no Kaibutsu-kun is a 2008 manga series that was adapted into a Fall 2012 Anime by Brains Base.Shizuku Mizutani only has one thing in mind: getting good grades. To accomplish this goal, Shizuku has little interest in anything else. However, after delivering lesson notes to her resident delinquent classmate Haru Yoshida, the latter is convinced that they are friends. Initially, Shizuku is intimidated by such a troublesome person, but she gradually notices that Haru is actually a kind person. When Haru confesses to Shizuku, an unlikely romance begins to blossom between them.The anime has been streamed by Crunchyroll and the manga has been picked up for a North American release by Kodansha USA, both under the title My Little Monster.
When Shizuku confesses to Haru, Haru gently rebuffs her as he doesn't think their "likes" are the same and thus it wouldn't work out if they dated then and there. However, Shizuku takes the rejection in stride and replies that she'll wait for him until he falls in love with her.
And when Haru finally does realize and reciprocate his feelings for Shizuku, it ironically ends up around the same time that Shizuku decides to completely focus on her studies and disregard any affection that she has for Haru.
Beware the Nice Ones: Micchan may seem like just an easygoing nice guy, but he can go toe to toe with an enraged Haru, and win.
Haru's intelligence also counts. Since his parents were told about their youngest son's intelligence, they paid more attention to him than Yuzan. This resulted in Haru being ignored by his older brother and him being picked on by Kenji. In his late teen years, Shizuku initially resents him because of his intelligence.
Book Dumb: Natsume and Sasayan get borderline passing grades, though he tends to fare better than her by a smidge. Otherwise, they're both grounded in common sense (well, except in areas relating to their own relationships), and play the secondary roles of either enlightening the emotionally clueless Shizuku and Haru or holding a discussion about the two.
Cool Shades: Micchan wears a pair of them at all times.
Domestic Abuse: Subverted. Just about anytime Shizuku gets hurt by Haru, it's by accident. Since Haru has such a terrifying temper, he somehow catches Shizuku in the crossfire of his rampage. These accidental attacks are the reason why Shizuku often demands Haru to stay away from her and glares at him.
Drunk on Milk: Natsume tends to drink lots of juice boxes when she's upset, and acts like a sad/angry drunk when she does.
First Kiss: At the end of the first episode of the anime. And Haru was totally disappointed by it. Shizuku on the other hand...
Generic Cuteness: Some characters, like Natsume, are explicitly stated to be very good looking but they aren't really drawn any cuter than the relatively more average lookers like Shizuku.
Green-Eyed Monster: Shizuku has her first taste of jealousy when Haru becomes popular with the girls at school. And Haru definitely does not like it whenever he stumbles upon Shizuku and Yamaken hanging out, knowing full well that the latter has feelings for the former.
House Husband: Shizuku's father. Since his business has gone under six times, he gets to spend more time with his son and daughter than his Workaholic wife.
I Just Want to Have Friends: Haru, Natsume, and Oshima. Surprisingly enough, the latter has a friend named Yu, but she doesn't make an official appearance until later.
In-Series Nickname: Sasahara is nicknamed "Sasayan", Natsume nicknaming Shizuku, "Mitti," and "Yamaken" for Kenichi Yamaguchi. Haru calls Ooshima "Class Rep" before she properly introduces herself to him, and Yamaken's gang has a habit of nicknaming Shizuku, "Study Bug."
Intelligence Equals Isolation: Played with. Shizuku has little to no friends prior to meeting Haru due to her constant focus on studying while Yamaken is intelligent and at times arrogant and merely hangs out with his gang because "idiots amuse [him]." Averted with Haru.
Just Friends: Defied, then Played Straight by Yamaken. After being rejected by Shizuku, he said had no intentions of remaining Just Friends with her. Later on, when he overcomes his pride and properly confesses to her and asks her to go steady with him, she rejects him again. This time though, he is less bitter about it and asks if he can take up her offer of being friends, to which she happily agrees.
Kid with the Leash: Invoked in just about every volume's cover. In-universe, Shizuku's advice is just about the only advice that Haru considers thoughtfully, and he does what he can to not get in her way when it comes to studying.
Lap Pillow: When Haru finds a sleeping Shizuku by the roof, he does this for her.
Love Triangle: Quite a few. The first one is between Shizuku, Haru, and Ooshima. Two other love triangles later sprout between Haru, Shizuku, and Yamaken and Sasayan, Natsume, and Micchan.
Megane: Yamaken occasionally wears glasses. Haru attempted wearing glasses to gain more popularity (and failed).
Moment Killer: Haru and Yamaken are often each other's moment killers with it comes to both of them trying to spend time with Shizuku.
Haru tends to be this in general because of his obliviousness.
No Sense of Personal Space: Afer Haru confesses to Shizuku a second time, he tries to get physically close to her. She draws the line after he licks her hand. He eventually learns to respect her personal space.
No Social Skills: Haru really does not know how to deal with people and instead resorts to glaring and violence in order to interact with others. He's slowly learning how to do so without his normal tactics, but he tends to fall back into it fairly often.
Also, Haru and Shizuku with their tendency to create barriers that prevent others from becoming close to them.
Not What It Looks Like: During the cultural festival, Shizuku and Yamaken get into this situation twice: 1) when Haru and Ooshima discover that they're together alone in a room (and eavesdropped on their conversation), and 2) when Yamaken's gang find Yamaken and Shizuku together and assume something happened between Yamaken and "Study Bug."
He Is Not My Boyfriend: Everyone merely assumes that Shizuku is Haru's girlfriend because they always hang out together, to Shizuku's annoyance on how the assumption has been apparently established as fact.
Their relationship does eventually enter into this territory later, though.
Smart People Wear Glasses: Yamaken occasionally wears glasses during cram school and has high marks that rival Shizuku's. Haru averts this by being quite intelligent but only tried wearing glasses to try and become popular.