Hero Killer: Inverted since he is a protagonist. At one point in the series nobody wants to take him on because he took down Rikiishi, Wolf and by technicality, Carlos. Fitting for someone known as "The Grim Reaper" and "Killer Joe"
How the Mighty Have Fallen: Rikiishi's death traumatizes him harder than expected; his aversion to hitting opponents in the head causes him to lose a lot of matches afterwards. This results in him deciding to fight up in the boonies, despite the fact that they fix the outcome of their matches.
Irony: Despite his nickname, Joe had only won against one person that he was said to have "killed". Although Riikishi dies, he had beaten Joe in the match via KO. While Carlos receives brain damage from Joe's fight the match was officially called a draw.
"The Reason You Suck" Speech: Calls out Ryuhi Kin on being completely full of himself, using his childhood trauma during the Korean War as if it's a badge to be proud of. He finishes off by saying that his actions don't make him superior, but in fact, inferior to men like Rikiishi, who didn't even have water to drink like Kin did and was willing to put himself under such conditions for the sake of having a match with a long-time friend. And this is all while he is beating the hell out of Kin in the match.
Weight Woe: A late growth spurt pushes him far past the weight limit from a bantamweight note at 57 kilos he could possibly even qualify for lightweight, which is three classes above; even more than what Rikiishi had to do. This becomes a problem when he jumps the gun and challenges Ryuhi Kin, especially when the latter devastates someone who went down from the lightweight class to challenge him.
Why Did It Have to Be Snakes?: After Rikiishi has passed away, Joe is afraid to hit his opponents in the head since that's what finished his rival.
Worthy Opponent: Considers most of his opponents as one, and in most cases they consider him one.
Throw the Dog a Bone: He gets a rude awakening once he's taken to the juvenile prison on account of not being the biggest and meanest kid he knows anymore, once he and Joe get into the pros it's shown that he's not very good at boxing and unlike Joe he can't handle the strenuous weight training that Danpei makes him go through due to his size and is ridiculed for it. However, he's shown to be very reliable to the Hayashi family market while Joe struggled to help at all, and eventually Noriko's parents trust him with the business and trust him with Noriko herself.
Anti-Villain: She antagonises Joe mostly during the first half of the series, then organizes most of Joe's fights, and, as he puts it, toys with his fate like a demon. She is, however, a good person when it counts.
Everyone Can See It: Pretty much everyone at Danpei's Gym thinks this regarding her and Joe. They're proven right in Volume 19.
Heroic BSOD: Just like Joe, she has one when Rikiishi dies. Unlike him, she recovers quickly.
Irony: Despite being the one that always leaves boxing matches whenever they get ugly, and that she cares a great deal for Joe's medical condition, in Joe's fight against Mendoza, she, is the only one who encourages Joe to fight to the bitter end and leave no regrets in the ring. This is despite the fact that Joe's punch-drunk syndrome is so bad at this point that he can't even see out of one of his eyes.
Love Epiphany: It's not until the matchup between Joe and Mendoza finally becomes a reality that she realizes that the only reason she sticks her nose into Joe's business is because she loves him.
My God, What Have I Done?: She's plagued with guilt after Carlos hints that he might not have been fighting seriously in his exhibition match against Joe. She's noticeably not her calm and aloof self during the real match between them at Korakuen Hall, fearing that she may have set him up to be killed in the ring.
All the bloodshed during the match between Carlos and Joe at Korakuen Hall becomes too much for her at one point.
The Ojou: She's a calm, soft-spoken girl from a rich family.
Silk Hiding Steel: Noted, and respected for being a big-time promoter in a sport considered to be strictly for men.
Stay in the Kitchen: Joe is not very fond of her presence in the boxing world. It should however, be noted that Joe is the only one who objects to it throughout the series. While other people were skeptical at first, they pay no attention to her gender once she shows she's more than capable about being a promoter.
Tender Tears: When she begs Joe to cancel the match against Mendoza once it's revealed that he has punch-drunk syndrome.
Tragic Keepsake: The boxing gloves she received from Joe in his last fight.
We Want Our Jerk Back: Of all people, she is the one that helps to convince Joe to get back into boxing after he accidentally kills Rikiishi. Though Joe fires back at her by saying that she's just toying with him, she makes a good point: Rikiishi definitely wouldn't have wanted him to stop boxing.
What the Hell, Hero?: Called out by Joe when she tries to leave during his match against Rikiishi in juvenile prison, with Joe pointing out that since she's the one that allowed it to happen, she should stick through it. This gets a Call Back during the match between Joe and Carlos, as she remembers that instance when she gets overwhelmed by how ugly the match between Joe and Carlos gets and convinces herself to stay.
Gets another callback when she leaves during Joe's fight with Mendoza, actually driving away, only to come back once she once again remembers Joe's match against Rikiishi.
Disc One Final Boss: A lot of hype is built up between the professional fight between him and Joe, both being regarded as up and coming talents. The match does not disappoint, but his untimely death afterwards does.
Foil: To Joe, obviously. While both are delinquents who take up boxing, Rikiishi is good-natured and looked up to by rest of the delinquents, while Joe is a Jerkass who is hated by many at first.
Also, Riikishi is sponsored and essentially taken care of by Shiraki Gym, a top class facility run by a wealthy family. Joe is sponsored by Danpei Tange, a trainer who's fallen out of graces with most of the boxing world and has no money to his name.
Weight Woe: Played for Drama. Since he's a Featherweight and Joe's a Bantamweight, he goes through great strains to keep himself two weight classes under his normal size in order for the two to have their fight. This results in the Shiraki Gym resorting to methods such as locking him behind a chained door (which he manages to break down) and tying up all the pipes in the facility. This hellish method also leads to his undoing as the effects from the extreme weight loss as well as the hard blow to the temple from Joe cause his death.
Worthy Opponent: Spends the beginning of his time in the story as a source of motivation for Joe to be a better boxer, and later on, it's revealed that he views Joe in the same way. All the more tragic when he dies.
Non-Idle Rich: Youko's grandpa, Rikishi's boss, and the owner of the Shiraki Gym.
Hopeless Suitor: It's very clear that she likes Joe, even to the point where people like Danpei notice. However, Joe's married to the world of boxing. Plus, her attempt to talk Joe into retirement makes it clear that nothing's gonna happen between them.
She Cleans Up Nicely: While she was never really that homely, she looks positively stunning once she perms her hair and gets rid of the drab clothing.
Afraid of Blood: Can't stand the sight of blood due to mistakenly killing his father.
Foil: To Joe. Kin's boxing style is methodical, while Joe's style is flashy and often unpredictable.
He also acts as a foil to Joe's other major opponents. Riikiishi and Carlos may have had radically different personalities outside of the ring, but once in the ring they fought with passion and treated the ring like if it were a life and death situation. Kin is stoic and dispassionate both in the ring and out of it, viewing boxing as "just a game".
Genius Bruiser: His boxing style is compared to that of a trained physician, as if he's dissecting them methodically.
Harmful to Minors: During the Korean War, he got to watch his mother be killed by a firebomb and the body burn to a crisp in front of him. He was around the same age as the current Slum Town kids when this happened. And that's not even describing what happened to his dad...
Hoist by His Own Petard: His phobia of blood makes him scream like a madman...and nothing else. Once one of his punches cuts Joe, he just stands there screaming, allowing Joe to shut him up for good by knocking him over the ropes.
Not So Stoic: Has a panic attack during Joe's No-Holds-Barred Beatdown of Danpei after he sees the latter on the ground bleeding profusely. His freak out manages to frighten everyone in the room, including Joe.
Also loses his cool while Joe calls him out on his assholish behavior during their match, swinging wildly and unpredictably which allows Joe to hit him with ease.
Out, Damned Spot!: In a similar vein to the Trope Namer, he causes a stir during his stay at the Asian Boxing Club by washing his hands and mumbling about them being bloody. All night, in fact. Quoth his trainer.
He sees blood on his hands that he can't wash away no matter how hard he tries.
"The Reason You Suck" Speech: Gives one to Joe, mocking him for not being able to control his weight like he can and is disgusted by how he builds himself up like a hungry champion, while he experienced real hunger and hardship starving in the streets of South Korea during the Korean War. Joe returns the favor during their match.
Ax-Crazy: Attacks people without abandon, regardless of if he's in a boxing match or not, and with little to no provocation whatsoever.
Foreign Wrestling Heel: Portrayed as this. When he comes out to fight, literally nobody cheers for him. Notable in that even jerkasses like Ryuhi Kin had fans in the stands; whenever Harimao's involved in a fight everyone wants to see him get beaten.
Freak Out: starts headbutting and biting Joe after getting knocked down one too many times.
Insane Troll Logic/Loophole Abuse: Lives off of it. Complain about him standing on the ropes? The rules state that he can't step outside of them but there's nothing about them that says he can't step on them. Complain about him jumping up in the air? Ref states that there's no rule against that either. Basically, whenever the crowd complains about his antics in the ring, expect them to be met with the ref saying that there Ain't No Rule.
Villainous Breakdown: Once Joe counters his corkscrew backflip punch with an even wilder technique he becomes terrified, realizing that he has met his match in Joe. As the announcer puts it, to him Joe is "a foe even wilder than himself existing in civilization".
Wild Child: Quickly proves that Shiraki was not joking when she said she had found an animal of a boxer.
The Ace: Strongly established then subverted once he fights Joe.
Achilles' Heel/Fatal Flaw: A very big one, as Joe points out in their match. Jose is great at dishing out damage, but not good at taking it.
Berserk Button: Joe is warned by the Hawaiian press that Mendoza hates loud-mouthed people and that they are one of the few things that make him upset. Joe, being Joe, only learns this fact the hard way when he mouths off to Mendoza and is dropped by a single punch.
Combat Pragmatist: Realizes that Joe can't see out of the left side of his eye during their match, no doubt due to injury taking a toll on his body. He doesn't hesitate to exploit that.
Defeating the Undefeatable: He is introduced in the series via knocking out Carlos in Round 1. And he's not afraid to show off the fact that he is this; when the series actually shows one of his fights, he allows his opponent, a guy nicknamed "The Hawaiian Bull", to hit him at point-blank range in order to show off that nobody's punches can leave a mark on him before effortlessly KOing his opponent. But later, we find out that he's not quite this trope.
Establishing Character Moment: When he first appears in the series proper he grabs Joe's shoulders and wishing him good luck. This was enough to leave bruises on Joe. That's how powerful he was.
Freak Out: Not even Mendoza can keep his composure against Joe. He loses all inhibitions and goes crazy when no matter what he throws at Joe, Joe just won't go down.
Jerk with a Heart of Gold: Despite treating Joe like crap (though to be fair like every other situation where he pisses someone off, Joe was asking for it), Mendoza respects him a great deal. That's why he's disappointed in their fight when Joe comes out with only one goal in mind.
Oh Crap: When Joe finds out that his display against the Hawaiian Bull was nothing more than an elaborate bluff: by recreating the situation in their match, Joe shows that holding a boxer's shoulder greatly reduces a boxer's upper body strength.
Politically Incorrect Hero: Calls Joe names such as "yellow brute" and "yellow sheep", but for the most part is respectful to the other Japanese characters in the story.
Heroic Antagonist Breakdown: Starts getting very philosophical (and not in the good kind) when Joe takes enough damage to cripple, if not outright kill someone —but Joe just keeps coming back off the mat no matter how many times he knocks him down.
Joe Yabuki...must have already died long ago...but then...who am I fighting with on the ring...? Am I fighting with his phantom...? Or am I trapped in a nightmare...?
Worthy Opponent: Considers Joe as one; in fact he considers him to be a better man than he is when despite taking inhumane amounts of damage, Joe continues to fight. Mendoza admits that at that point he would give up, thinking more about returning home to his family.
Actually enforced in-story by his trainer Harry Robert. When asked by the media, Robert says that the reason Carlos plays around with his opponents is because when he gets serious, no other gym (understandably) wants their boxers to challenge him.
Came Back Wrong: When he returns after being "retired" by Mendoza, he is pretty much a shell of his former self.
On his departure from Japan, he suddenly falls down while saying his goodbyes to the Japanese people. After his disastrous fight against Jose Mendoza, Robert reveals to the press that Carlos was having difficulty doing simple tasks such as ascending the stairs, something that usually happens to boxers that suffer from Punch-Drunk Syndrome.
At the end of the 4th round in his match against Joe, Robert talks to him, only for him to be ignored. Then he starts to blatantly fight wild and dirty until he's knocked down by Joe, who also starts to fight dirty. His shocked expression when Joe knocks him down indicates that Carlos may have not been completely there when committing all of those fouls, signifying the start of his brain damage.
Freak Out: Pretty much loses his shit and starts to fight dirty against Joe after the fourth round in their bout at Korakuen Hall, going from simple fouls such as elbow strikes and head-butts to attempting to attack an already downed Joe, knocking the referee out of his way to do so.
Jerk with a Heart of Gold: Regardless of necessary reasons why, his method of baiting opponents into getting the living daylights beaten out of them tend to rub some readers the wrong way. Apart from that he shows no jerkish tendencies and for the most part, is a good guy.
Let's Get Dangerous: As noted above. He may be a charismatic playboy but don't ever think that his ranking in the world is for show.
Oh Crap: In his bout against Joe at Korakuen Hall.
When at the beginning of the match, he realizes that Joe isn't the same person he fought during their spar and exhibition match
When Joe manages to make it to his feet and continue fighting after Carlos brutally counters the rope trick that Joe used to surprise him in their exhibition match.
Finally, when Joe knocks him down even after he's countered Joe's rope techniques. It completely changes the complexion of the fight as Carlos becomes noticeably sloppier in his movements.
Put on a Bus: After his disastrous fight against Mendoza he retires and was seen wandering the streets of Venezuela.
Anti-Villain: A very benevolent yakuza even before Joe befriends him.
Defeat Means Friendship: When he calls Wolf a disgrace of a person after beating him up, he is in turn beaten up by an enraged Joe.
First time, his actions described in Genre Savvy lay out a blueprint for many of the other boxers on how to beat a reinvigorated Joe, and the losses that Joe picks up destroys nearly all of his reputation in the boxing world.
Second time, his overconfidence brings out the real Carlos in their match and he's literally beaten before he realizes it. Everyone else that was willing to fight Carlos under the thought that he wasn't very good realizes that they are completely screwed because they can't back out. Carlos was more than happy to prove them correct, brutalizing all of them.