Its title was changed in 1996 to just Doctor K, presenting Kazuya being framed for an attempt on the American president's life. The story ended in 1998 before being followed in 2004 by the sequel K2 which is still ongoing as of 2022.
This manga features the following tropes:
- Alternate Character Reading: In the sequel, Kazunari's name is spelled with kanji that can also be pronounced as "Kazuya".
- Arranged Marriage: Between Kazuya's parents, Kazuoki and Kyoko.
- As You Know: Returning supporting characters often comment on what happened the last time they met K. When Kazuya's uncle Raisuke is seen for the second time, the narrator even asks the reader if they still remember him.
- Author Tract:
- Naturally, several chapters deal with the importance of all physicians and others are about corruption on the medical establishment.
- Chapter 63 ends with the narrator remarking that Japan is seriously outmoded by other countries when it comes to organ transplants due to lack of donors, difficulty to have consent from a dead person's family and the unpreparedness of their medical system.
- Chapter 69 involves a girl who has to pretend being a boy to play professional Baseball. While the narrative supports men and women playing the sport on equal terms, both Takashina and Kazuya speak against trans people (Takashina making crude remarks while K argues people should accept their biological gender) when the subject comes up.
- Badass Family:
- Each head of Kazuya's family is trained to become a master surgeon who can treat anything.
- The Saijo clan to which Kazuya's mother belonged worked for Japan's goverment since the Edo Period.
- Big Damn Heroes: When Kazuya is gravely ill from a unknown cause, every doctor he's helped through the series comes to his aid and together they manage to find a solution.
- Bold Inflation: In the original Japanese version, for some reason Kazuya's name is always emphasized by being spelled in the Latin alphabet. As such, it is turned into this trope for translations.
- Career-Ending Injury:
- A volleyball player called Sadahisa Otani who's friends with Kazuya gets his right arm ripped off by a train while saving a boy from the tracks. Kazuya puts him back together and gives him a training regimen to be performed until he gains his grip back. At the end of the story, the player does manage to earn the gold medal for his team at the Olympics.
- A young F-1 racer named Oda gets his eyes damaged by radiator steam while working on his car. Later his teammate, an expy of Alain Prost, burns to death in a crash but manages to protect his eyes so that their cornea can be donated to Oda.
- Sadahisa's brother Tatsumi, a Track and Field runner, is hit by a car in a later story and three ligaments on his right leg are severed. Kazuya provides him with an ingenious surgery and the motivation needed to get back to form. Tatsumi's rival Shuichi had been taking doping drugs from Dr. Tetsu and collapses from the side-effects after a very close victory. The media considers him virtually retired, but Kazuya and Sadahisa start helping him recover and redeem himself from his mistake as well.
- Character Title: "Doctor K" refers to both Kazuya and his ancestors, who apparently all had names that started with K.
- Cool Shades: Dr. Kaiser wears Rodenstock shades to a conference because he's a true patriot... and to hide his jaundiced eyes — a sign that he's suffering from liver failure.
- Dragon Their Feet: Hashizume repeatedly targets Kazuya for the death of his boss Hidemasa even after the former president's grandson gives up on it. However, when Hashizume finally corners Kazuya and is in the middle of stabbing him to death, it just so happens K is operating on his own son. The hitman is forced to help out and ironically has to prevent all the other people from Jonan University from finishing K off.
- Drowning My Sorrows: Kazuya finds his former teacher Dr. Ogaki down in the dumps from being set up to take the fall from the death of a terminal patient. When a critical patient comes to his clinic, Ogaki tries to drive him away due to a lack of tools, but Kazuya argues that would mean falling to the level of the scum who framed him. Together they improvise a solution until an ambulance comes, which restores Ogaki's confidence.
- Drugs Are Bad: A story arc starting in chapter 135 starts with Dr. Quaid asking Kazuya and Asakura to treat his son, who has fallen into a coma from drug overdose. Jeff Ekland, the vice-chairman of the Quaid Foundation, sends Kazuya and Tetsu alongside a squad of soldiers to curb drug trafficking in America by capturing a drug kingpin called Silvara on the border between Brazil and Colombia. Things turn complicated when Kazuya realizes the nefarious Tetsu had vaccinated everyone with plague capsules to prevent desertion and that the soldiers were actually under orders to kill Silvara. Kazuya ends up encountering the man himself and learns that not only the locals depend on the drug plantations to make a living but also that Jeff is actually their biggest client. The most xenophobic man alive, Jeff intends to take over Silvara's operations, redirect all of it to Japan to ruin the country and also to get Kazuya and Asakura assassinated while he's at it.
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Dyeing for Your Art: The actor Suematsu Shinji, in after learning that he has a disease that could result in his blood vessels bursting at any moment, refuses to get it treated because the change it causes in his personality makes him a better actor. Luckily Kazuya operated on him after his wife slipped him a mickey. - Dying Declaration of Love: Ryuichi tells a story of how he fought to become a doctor to earn the hand of his mentor Fumiyo in marriage, only to learn she suffered from terminal cancer and accidentally hasten her death in his grief during their last conversation. He keeps a x-ray marked with an "sa" that Fumiyo gifted him in her final moments, but doesn't understand what it means until Kazuya turns it upside down and notes the trachea in the picture forms a "Yes" with the two letters.
- Evil Counterpart: Dr. "T" Tetsu, who is willing to perform nefarious surgeries and treatments to enhance people's abilities.
- Evil Old Folks: An old university president who's suffering from a heart disease stages a traffic accident to make K transplant a young man's heart into him. Instead, K secretly heals both the president and the victim. The old man dies anyway out of shock when he realizes what happened.
- Expy:
- Kazuo Mafune once worked as an assistant to Tetsuo Hara, which explains why Dr. Kazuya is pretty much Kenshiro with a slighty different haircut. His personality and some of his superhuman traits all match Ken's. Hell, he even wears a typical post-apocalyptic cloak everywhere in a plain contemporary setting.
- German doctor Wilhelm Kaiser looks just like Stroheim from Jojos Bizarre Adventure and comes complete with the "German X is the greatest in the world" catchphrase. This manga was running concurrently with Battle Tendency at the time.
- In chapter 92, Kakyoin from that same series appears as the evil Dr. Sanada Takeshi. His design is pretty much shamelessly the same, and even his plan to set a parasite upon K is analogous to Kakyoin possessing a teacher with Hierophant Green when he's first introduced as a villain. That Jotaro already was cut from Kenshiro's cloth and like him Kazuya gets to personally judge Sanada because the police is made to ignore the villain's next ploy, makes the whole reference fit like hand in glove.
- Feel No Pain:
- In one story Kazuya is kidnapped to work for the royal army of Qasar. The King wants him to "remodel" his soldiers into unrelenting killing machines, but K refuses to have any involvement in that. Then another doctor, Tetsu, shows up and inflicts this trope on the soldiers via a treatment that's supposed to be used to relieve the pain of patients with terminal cancer. The soldiers steadily lose their humanity as they fight and become willing to storm a hospital full of hostages. However, their leader Satoki comes to his senses when he accidentally shoots his own fiancée.
- After figuring out Satoki can still be cured and doing so, Kazuya sneaks into the King's bedroom and does neurosurgery to deprive him of pain for a set amount of time. On the next day the King suffers from various injuries without realizing it and becomes greatly worried. Upon hearing Satoki's confession of what they had done and why, the King acknowledges how he caused such suffering to his loyal subjects and begins to strive for a peaceful resolution to the civil war in his country.
- A Friend in Need: Dr. Asakura misses a chance at a promotion to support Kazuya in an extremely difficult double surgery to save their friend Takashina. He gets fired afterwards by the board of directors, but the good-natured president of the hospital remarks Asakura is better off that way.
- Friendly Enemy:
- Kazuya once gets stuck on an american battleship where the crew was supposedly suffering from food poisoning but was actually under the effects of damaged bioweapons they were secretly transporting. Kazuya was given no information or equipment to handle this, but then a soviet submarine comes and hits the ship with a torpedo filled with medicine because their goverment couldn't let Kazuya meet his doom there. The captains from both vessels bid farewell hoping to never have to face each other in combat.
- The drug kingpin Silvara is amicable to Kazuya, as he's familiar with his reputation and knows he shouldn't be killed. Even when Silvara's drug plantations end up destroyed he asks his forces to spare Kazuya and Tetsu on the basis that they're noncombatants and gets them sent back to America.
- Gag Penis: Dr. Yasunori Mamo has a habit of casually walking around bottomless, much to the shock of anyone who sees him like this. Even his character profile page has him half-naked with a mosaic over his genitals.
- Generation Xerox: Kazuya looks and dresses like his late father Kazuoki. He's led a reclusive life much similar to that of his father as well.
- Genius Bruiser: Kazuya is both very knowledgeable and built like a tank.
- Gratuitous English: The volume covers for K2 contain the English Tagline "The man with flesh of wild beasts, genius brains, and most of all, superhuman surgical knife technique".
- Grew Beyond Their Programming: Dr. Yasunori builds a machine called Mars to cure his cancer and forbids anyone from interrupting the procedure unless he dies and a lamp flashes outside as a warning. The machine reduces as much of the cancer with thermotherapy as Yasunori's body can stand and then goes against its directives by flashing the lamp, which lets the other doctors retrieve him and remove the rest of the cancer via surgery.
- Heel Realization: A group of spoiled rich kids ended up getting food poisoning while camping in the woods. Earlier one of them ended up kicking a stray dog after it had attacked him, however it turns out it was trying to warn him not to eat the rotten food.
- The Hero Dies: The radioactive accident Kazuya lost his father on causes him to develop gastric cancer midway through the series. Despite undergoing surgery, the disease reappears at the end and the sequel confirms Kazuya passed away at 36 years old.
- Hero Stole My Bike: Dr. Ogaki stops a man on the street and takes his bike so he can use its tire as an improvised balloon to stop the internal bleeding on a patient's esophagus.
- Heroes Love Dogs: A stray dog once helps Kazuya save food-poisoned people and later helps him identify which person in a group is suffering from diabetes. Kazuya names him "Sirius," after the main star of Canis Major, and gives him to Nanase.
- Heroic Sacrifice:
- During an accident in a nuclear plant, Kazuoki got locked inside a highly radioactive room to keep Kazuya and other people safe in the next room and died from radiation poisoning. His body was found still standing after he finished giving Kazuya surgery instructions to save an old friend.
- Dr. Nanase gets locked inside a sealed-off room without air circulation and with a severely injured Kazuya. She manages to fix his bleeding arm and give him the single oxygen tank available before passing out. Thankfully, Kazuya wakes up right after and uses a chemical reaction with his own blood and Oxydolum to produce more oxygen until the bad guys open the place again.
- When a young Kazuya and his mother Kyoko get caught in a landslide, the boy suffers from severe blood loss and his type is Le(a-b-) of all things. By the end of the story Kyoko locks herself with him and transfuses her blood until she dies in his place.
- When Dr. Sorimachi makes a desperate deal with the black market to obtain a kidney for a patient, he finds it came from Cunanan, a victim of organ traffickers who then happens to get sent for treatment on the hospital he works in. Sorimachi suffers mortal injuries when he stays behind to retrieve Cunanan's other kidney from the traffickers' headquarters.
- Hashizume is beaten and stabbed to death while guarding the operation room a heavily injured Kazuya was being treated in, in gratitude for his hated enemy having saved his son's life.
- Karma Houdini: Dr. Tetsu convinces Shuichi to take doping drugs and runs the guy's rival, Tatsumi, over with a car. Tatsumi never presses charges against Tetsu and keeps what Shuichi is doing a secret from the media. After recovering from his injuries, Tatsumi narrowly loses against Shuichi, which makes Tetsu feel validated despite Shuichi nearly dying from the side-effects of his treatment.
- Kick the Dog: The japanese media takes Rosha Ram from India with the pretense of letting him heal people with his mysterious powers. Instead, they drop him in a reality show and poison a dog to near-death so he can heal it. Rosha sees through them instantly and is further horrified to see his powers are doing nothing to help the poor pup. Luckily, Kazuya arrives in time to help them.
- Know When to Fold 'Em: The staff of Jonan University target Kazuya a couple of times after he indirectly caused the death of their scumbag president Hidemasa early in the series. However, when their attempt to frame K for botching the stomach surgery on a patient is foiled and becomes a media scandal, Hidemasa's grandson calls it quits... until some time later, and that causes his downfall.
- Later-Installment Weirdness: Over the years, the story stopped focusing on action and Kazuya's super-human feats. Once he starts working at a college doctor, some scenarios don't even feature him.
- Legacy Character: In K2, Kazuhito inherits Kazuya's name and legacy after the doctor's passing.
- Lightning Can Do Anything: Upon examining Rosha Ram, a indian wanderer who supposedly has healing powers, Kazuya realizes the lightning bolt that struck him as a child messed up with his nerves such that they concentrate the electric currents within his body up to 300 volts, which isn't that god-like but has a variety of applications for medicine.
- MacGuffin Super-Person:
- Kazuya is a master surgeon who is sought by powerful and dangerous men all over the world. His sudden passing without any descendants sends the medical world into chaos, to the point of people resorting to cloning to preserve his intelect.
- In the sequel, Kazunari is a perfect clone of Kazuya who finds himself caught in all sorts of danger for the value he possesses.
- Manly Tears: A young Kazuya sheds tears when Kazuoki becomes doomed to die locked inside a radioactive room. He then wipes them and bravely goes to work on the wounded Dr. Yanagawa as Kazuoki gives directions.
- Men Don't Cry: Kyoko told her son Kazuya this as part of her Dying Speech, and so he rarely cries.
- The Mole: During the operation in South America to destroy Silvara's drug plantation, one of the soldiers in the team is tasked with killing all the others. This turns out to be their very leader Stewart, who only did it for the thrill of killing.
- No Good Deed Goes Unpunished: Otani Sadahisa is an Olympic volleyball player who is said to be Japan’s hope of winning the gold. While out jogging, he comes across a kid that had passed out on the tracks. While rescuing the kid, a train passed and ripped off Sadahisa’s arm. The Olympic enforcement committee was furious with him and accused him of betraying his country. When he is let back on the team after his reattachment surgery and rehab, they consider him nothing but dead weight, only to change their tune when he leads the team to victory. By this point, he sees them for who they truly are and refuses to let them save face.
- Not the Fall That Kills You…: Kazuya is forced to jump off the fourth floor of a building to save a patient from Jonan University's goons. He falls through a tree to try to cushion himself, but is still severely injured.
- It's Not You, It's My Enemies: Kazuya's father Kazuoki left a patient he loved because he, like every other man in his family, is hunted by evil and corrupt people for his skills.
- Oddly Named Sequel: The last few arcs were published as just Doctor K and the sequel is K2.
- Paper-Thin Disguise: One villain somehow can't recognize the tough guy with bracelets and a characteristic cloak before him just because he has a magazine over his face.
- Reasonable Authority Figure: Kazuya is paranoid that every authority figure wants to take his skills for their selfish purposes, but the story also shows several who can be reasoned with or that are even looking out for him from afar.
- Recycled In Space: This series can be described as "Black Jack with Kenshiro in Jack's place".
- Roaring Rampage of Revenge: When Sanada begins plotting to discredit and assassinate all of Kazuya's friends and gets the police to turn a blind eye to it, Kazuya gets so enraged he walks up to Sanada's apartment to brutalize the guy, even if he has to swear off being a doctor depending of what happens.
- Screw the Rules, I'm Doing What's Right!:
- In one story, K is forced to use the corpse of a pilot who suddenly died and crashed the helicopter he was in for a skin graft surgery on another passenger, a attorney with fatal burn injuries, despite the man declaring it would be against the law to do so, and being willing to die if it meant K could be hired into his medical institute without any more complications. Dr. Asakura attempts to help as well, but gets knocked out by K.
- A rescue worker named Mochiji makes a call to a hospital regarding the victim of a traffic accident his group doesn't have enough time to bring to safety. On the other side of the line, K warns Mochiji that he'll have to perform a surgery by following his instructions, but will also be branded a criminal for doing so without medical qualifications. Mochiji still agrees, feeling sympathy for the patient since he also used to be a bike racer in his youth.
- When an idol singer refuses to remove a malignant polyp from her throat because it would mean losing her voice, Doctor Kazuya ends up knocking her out and taking her to the hospital refusing to sit by and watch a patient die. Luckily, things work out, as he is able to create an artificial polyp using silicon.
- The actor Suematsu Shinji, in after learning that he has a disease that could result in his blood vessels bursting at any moment, refuses to get it treated because the change it causes in his personality makes him a better actor. Luckily Kazuya operated on him after his wife slipped him a mickey.
- Sudden Sequel Death Syndrome: The title character himself dies from cancer between the original series and the sequel.
- Super-Senses: Kazuya was once just making his way downtown when he heard a man groaning in pain on the inside of a house on the opposite side of the street.
- Superpowered Evil Side: Suematsu Shinji is a downplayed example. He suddenly becomes a Master Actor due to insufficient blood flow to his brain causing a drastic change in his personality.
- Tag Line: "Hard Boiled Medical Legend".
- Teeth-Clenched Teamwork: When doctors Kazuya and Tetsu are saved from the traitorous Stewart by a barely alive Hicks, who's missing an arm and has guts leaking out of his abdomen, they waste no time in cooperating to perform surgery on him while on the way back to America in a helicopter. Tetsu makes the effort of helping Kazuya reattach the arm even if he thinks it's impossible under the circunstances, while Kazuya can't help but acknowledge the villain's surgical skills as well.
- The Power of Acting: Suematsu Shinji convinced himself that his disease was causing his improved performance. Kazuya kept the operation that saved him a secret so he wouldn’t lose his oddly placed self-confidence. His wife even cried and desperately tried to convince him to have the operation.
- The Topic of Cancer: Gastric cancer is what does Kazuya in. In the sequel, Dr. Tetsu and Ogaki also suffer from the disease but Ogaki manages to fully heal.
- This Is Unforgivable!: This phrase came up a few times early on whenever Kazuya caught sight of corruption in the medical establishment, but ended up becoming an Abandoned Catch Phrase.
- Thou Shalt Not Kill: Kazuya might be designed after Kenshiro but as a doctor he upholds the Hippocratic Oath and generally doesn't condone violence... Generally...
- He seriously considers kiling Sanada in response to him trying to assassinate his friends, but can't bring himself to let the villain die from what would've been a mortal wound.
- Kazuya takes part in the operation against the kingpin Silvara under the condition that that he'll be captured alive, but it soon turns out the soldiers involved had no intention of doing that. After the squad engages in combat with guerillas, Kazuya takes the time to perform first-aid on the one surviving enemy and takes him to safety. The squad moves ahead of Kazuya, but neither the leader Stewart or even Tetsu outright disagree with his way of thinking.
- Took a Level in Jerkass: The actor Suematsu Shinji goes from a Gentle Giant to a violent thug due to Cerebral Artiovenous Malformation.
- Tragic Keepsake: Kazuoki passed down his cloak to Kazuya shortly before his death.
- Tranquil Fury: Kyoko's brother Raisuke berates Kazuoki for calmly saying "her time had come" after failing to save her, but realizes the man can barely contain himself as well. In contrast to both of them, kid Kazuya accepts her sacrifice and death surprisingly well.
- Villains Want Mercy: Kazuya confronts Sanada to beat him to a pulp and possibly kill him for trying to slander and assassinate his friends, but once Sanada starts begging for forgiveness Kazuya lets go and begins to leave. Sanada then attemps to backstab Kazuya on the back of the head, so K actually mortally wounds him in response by puncturing his lungs. However, Kazuya ultimately can't bring himself to let the guy die in agony and full of regrets so he calls for an ambulance to save him.
- Your Mind Makes It Real: One story revolves around the Cerebral Artiovenous Malformation in Suematsu Shinji creating a Superpowered Evil Side, making him a Master Actor. However, it turned out that he had been secretly cured by Kazuya.
