Childhood Marriage Promise: He promised to marry his childhood friend if they ever meet again. It's eventually revealed that he, Chitoge and Kosaki played together as children and he visited Marika in the hospital, and promised all three.
Clueless Chick Magnet: He was actually very popular with the girls in middle school, but too dense to figure it out. In the present, other than Marika he doesn't really notice anyone else's feelings.
Jerk with a Heart of Gold: He can be brash and rude, yet his luck with women probably stems from the fact that no matter how annoying he may find them he still wants them to be happy, and will go through a lot to make sure they are.
KidAnova: He made promises with not just one, but three girls when he was five.
Loose Lips: Initially, Raku just can't help denying his relationship with Chitoge, even though it is made very clear to him that his life will be in danger if that relationship is exposed as phony.
Love Makes You Dumb: His crush on Kosaki can severely affect his rationality, dangerously steer him towards Too Dumb to Live territory. One example is when being in a open-air bath full of women due to Claude's scheme, he manages to find a connecting drain which can get him out undetected. However, he hesitates when the girls gleefully tease Kosaki about who her first love is, making her run to where Raku is and block the exit before he can reach it. He only manages to escape thanks to Chitoge, who berates him for wasting his chance. Even worse, since he subconsciously believes that Kosaki is too good for him, he just assumes that the girl he pines for doesn't return his affections, despite many signs of the contrary.
Mistaken for Cheating: This is why Haru hates him so much at first, believing him to be lusting for her sister while being in a relationship with Chitoge, unaware that said relationship is fake. However, Kosaki isn't actually the only girl he has feelings for...
Supreme Chef: He is a great cook. He often makes food for his yakuza subordinates. He can even create new delicious recipes.
Too Dumb to Live: This guy just can't keep his mouth shut about his fake relationship in order to protect his own life, but has coped better over time. Still, his crush on Kosaki can still cloud his judgement, making his life unnecessarily in danger.
Unwanted Harem: He only admits to liking Kosaki, but is in denial about Chitoge. To make matters worse, he also has to deal with Tsugumi and Marika and he has displayed an attraction to both of them from time to time as well. Eventually, he also gets Kosaki's sister Haru and his childhood friend and new teacher Yui included in his harem.
Tsundere: She's abrasive, haughty and violent to Raku when she actually doesn't hate him as much as she claims. She continues to act the same even after actually falling in love with him, resulting in herself lampshading her inability to be honest about her feelings.
Cannot Spit It Out: She gets opportunity after opportunity to tell Raku how she feels about him, but never takes the chance. Even if she does try to confess, something will prevent her message from getting through to him.
Beauty Mark: Has one beneath the corner of her right eye.
Bifauxnen: Due to her Tomboyish Name and her tendency to wear clothing intended for men, practically everyone mistakes her for a pretty boy. Claude still hasn't figured out that she's a girl after knowing her for ten years. Tsugumi isn't really bothered by it so she usually doesn't correct people about her gender.
D-Cup Distress: She's very uncomfortable with her large breasts, as seen in episode 18, especially because Chitoge made her wear a skimpy swimsuit. Both Chitoge and Marika groping her shortly afterwards didn't help much.
Even the Girls Want Her: After Seishirou is discovered to be a girl by the students, one of the boys mentions that the girls should stop paying attention to her now. Unfortunately for them, the girls still fawn over her, and rush over shortly after he says that.
Gag Boobs: Her bust, being the biggest among the main female cast, is used as a source of humor from time to time.
Raku's self-proclaimed fiancée and the daughter of the police commissioner.
Accent Relapse: Her native backwater-sounding dialect is completely at odds with the cultured persona she cultivates, so she takes great care to speak like the others. It reverts when she's completely flustered, becomes angry, or being visited by a childhood friend from her home.
A-Cup Angst: While she's not flat-chested, she does seem to lament that Seishirou has bigger breasts than her.
Bad Liar: Normally when asked about her past she feigns ignorance and avoids the question, but if forced to lie, it's often extremely obvious.
Foil: Marika serves as a foil to Kosaki. Both are girly girls head over heels for Raku, but, unlike Kosaki, Marika has no problem being completely open about her feelings, aggressively pursuing him, whereas Kosaki usually needs Ruri's help to summon any courage.
Forgotten First Meeting: Another forgotten childhood friend of Raku. Marika doesn't take it well when she finds out Raku forgot about her after she devoted her whole life to him. She was also friends with Chitogi, Kosaki and Tsugumi.
Genre Savvy: She seems to know about Chitoge's antics, and believes Raku is being forced into that relationship.
Girly Girl: Became like this to be Raku's ideal woman.
Short Hair With Tail: Most of her hair only reaches her chin, but two long "tails" are grown out on both sides.
Single-Target Sexuality: She has been in love with Raku all her life, never showing the slightest interest in anyone else. Of the girls that took the Love Potion that caused them to fall for Seishirou, she is the only one able to resist.
Sitcom Arch-Nemesis: She seems to actually enjoy being this to the other girls, especially Chitoge and Tsugumi.
Also with Yui who enjoys teasing and messing with Marika, but actually adores her. Marika, on the other hand, despises Yui.
Supreme Chef: Capable of making extravagant meals that both look and taste good. She says she has been honing her cooking skills for his sake. She even has a license for puffer fish preparation, something heavily regulated and quite difficult to obtain since the slightest misstep in preparing said fish can be literally lethal.
The Tease: Loves to do this towards Raku. She takes it up a notch anytime Chitoge is watching just to get a reaction out of her.
Troll: She enjoys forcing Raku into embarrassing situations and annoying her love rivals.
What the Hell, Hero?: Marika loses her usual demeanor as Raku delivers a stream of Armor Piercing Questions about not remembering who she was and only having vague memories of the meeting ten years ago. She lambastes him, stating everything she's done for him in the last ten years, such as thinking about him every day and growing her hair longer because he said he didn't like girls with short hair.
Voiced by: Koji Fujiyoshi (vomic), Yuuki Kaji (anime)
Jerk with a Heart of Gold: Despite his constant teasing, Shuu is quick to notice if any of his "friends" are hiding something or feeling down, and in his own way will try to help.
Megane: He actually seems to be proud of his glasses, acting as if they give him special privileges.
Obfuscating Stupidity: He's actually quite observant and perceptive, but prefers to act like a goof most of the time.
Shipper on Deck: He tends to support the Raku X Chitoge ship, though he doesn't seem to mind watching the other girls go after Raku as well.
Stepford Smiler: Part of his tendency to not let his actual feelings show that much, he went around smiling and acting cheerful when he learned Kyoko-sensei was getting married and retiring. Raku saw through it and mentioned that he'd had said tendency since he was a little boy.
Academic Athlete: She gets pretty good grades and is also the best swimmer of the school swim club. It's revealed in Chapter 102 that she has broken several swimming records during middle school and is known as "The Mermaid."
When She Smiles: Played with. Shuu gives her a picture he secretly snapped of a rare candid moment of her smiling right after she regretted not smiling in the last photo of her with her grandfather just before he died. It's quietly hinted that Shuu liked seeing that side of her.
Raku's childhood friend who is a couple of years older than him, the don of a Chinese organization and the main cast's new homeroom teacher. She is also the holder of the fourth, and supposed last, key.
I Want My Beloved to Be Happy: She eventually realizes she has a crush on Raku, but decides to support her sister instead and let them be happy together.
Jerkass: To Raku, whom she treats with nothing but irrational and petty contempt.
Loves My Alter Ego: She's in love with the "prince" who saved her from a gang, but she doesn't know and refuses to believe he is actually Raku. She eventually realizes those two people are one, and has trouble abandoning her love with Raku for the sake of her sister since then.
Matchmaker Crush: She decides to support her sister's relationship with Raku, but there's the issue of her own feelings for him.
My Sister Is Off Limits: Doesn't want Raku to be with her sister at first due to a misunderstanding. After realizing Raku is a really nice guy and that her sister likes him, she decides to support their relationship.
No Sense of Direction: Sometimes she can't even tell what floor she is on in a mall even though there is a sign.
Rescue Romance: She loves the "prince" (Raku) who saved her from a gang.