- Ambiguously Jewish
- Charles Atlas Superpower: His strength is a combination of this and his right hand.
- Genius Bruiser: In school, his best subjects were Physics and Music.
- Expy: Of Kenshiro.
- I Know Kung-Fu: Naike Kenpo is a Shaolin martial art. Referred to as Qigong in the movie.
- Ki Attacks: Naike Kenpo specializes in this trope.
- Kamehame Hadoken: KANTSU REPPA!!!
- KANTSU REKKEN!!!
- Kamehame Hadoken: KANTSU REPPA!!!
- Made of Iron
- Red Right Hand: His right hand has the Star of David embedded onto it and is the source of his strength.
- Super Strength: Enough to punch through giant brick walls and peoples bodies with ease. See Red Right Hand and Charles Atlas Superpower.
- Dark Messiah
- Evil Twin: To Riki-Oh.
- Mind over Matter: He posesses very powerful psychokinesis.
- No Swastikas: Averted. See below.
- Physical God: The people of the Cape referred to him as the "Living God".
- Red Right Hand: His left hand has a swastika embedded onto it and is the source of his psychic powers.
- Woobie, Destroyer of Worlds: He was abandoned by Riki-Oh while playing Hide and Seek, and now he's practically trying to wipe out the human race.
- Luke, I Might Be Your Father: She might be the daughter of Adolf Hitler.
- Mama Bear: To Riki-Oh and Nachi.
- Big Bad: Of the Prison Arc.
- Cool Shades
- Deceptive Disciple: He too was taught Naike Kenpo by Cho Zenki.
- No Name Given
- One-Winged Angel: He becomes a Hulk-like giant whilst fighting Riki-Oh. He says he was able to do so by training his muscles with Kokiko (essentially Qigong).
- Dirty Old Man: He has a collection of porn in his office.
- The Dragon: To the Warden.
- Glass Eye
- Hook Hand
- Combat Pragmatist: He hid a nail in his anus to try and stab Riki-Oh with.
- Kick the Dog: He deliberately destroyed a toy made by Wakamatsu who was going to send it to his son.
- Combat Pragmatist: He fought Riki-Oh using a knife, glass shards and his own intestines.
- Dub Name Change: He's more well known by the name 'Oscar'.
- Tattooed Crook
- Big Bad: Of the Cape Arc.
- Cool Sword: His katana, its made from the metals found in a meteorite and can cut through virtually anything.
- Expy: Of Yasunori Kato. He is the inspiration for the design of M. Bison.
- I Like Swords:
- Mercy Kill: He shot 119 of his own men that were slowly dying from a gas attack. He keeps a rose garden containing 119 of them.
- Villain Decay: Built up as the big bad of the Cape Arc by being the leader of the cape and easily defeating Riki-Oh in a fight...only to later go crazy, paint his face, wear weird head gear, and is suddenly much easier for Riki to beat.
- Justified, as he was completely focused and composed in the first fight with Riki-Oh. In their second duel, he's gone insane, and Riki-Oh's been honing his skills in battles prior to this one.
- Villainous Breakdown: Upon realizing that he's going to be abandoned by the Big Bad, Washizaki goes positively nuts: putting on face paint, strapping a pair of flashlights to his head in an imitation of the way candles are worn in certain Shinto rituals, and trying to kill Nachi and his unarmed followers...not to mention slaughtering any of his own men if they question his actions.
Robotomi 560SEL-Mark. II
- Adaptation Name Change: He's called "Atomic Robo" in the OVA.
- What Measure Is a Non-Human?: Only Riki-Oh saw him as a person.
- Badass Mustache: He calls it his "Mustache of Pride".
- Expy: Of Mr. Heart.
- Fat Bastard: Even more so than Bandoh.
- Kevlard: His body fat can suck people's arms in and snap the bones.
- Stout Strength
- An Arm and a Leg: A somewhat mild example—when Aneyama punishes him for failing to kill Riki-Oh in the past, Mizuguchi ends up losing his nose during the ensuing torture.
- Ain't Too Proud to Beg: When Riki-Oh tries to corner him, he tries to bribe Riki-Oh with money to spare his life. This doesn't end well for him.
- Asshole Victim: He gets tortured by Aneyama for failing to kill Riki-Oh. Considering that this happens after we learn about his more unsavory aspects, it's hard to feel sorry for him.
- Cold-Blooded Torture: He's implied to indulge in this, as he threatens Riki-Oh with brutal dismemberment before death, and delights in the idea of Riki-Oh being force-fed sulfuric acid.
- Faux Affably Evil: He's introduced as a rather pragmatic, laid-back gangster who took the daughter of one of his underlings under his wing after Riki-Oh killed said underling in a duel. Before the arc is finished, however, this relatively nonchalant facade is revealed to be masking some rather unpleasant habits...
- I Am A Humanitarian: It's implied that his chef includes human sashimi as part of his diet.
- Killed Mid-Sentence: He's slain by one of his own lieutenants just as he's about to give up the same of Riki-Oh's true father.
- Non-Action Big Bad: Despite trying to blow Riki-Oh up with a rocket launcher in his introduction, he's ultimately helpless when Riki-Oh confronts him after killing off his lieutenants.
- No Kill Like Overkill: When he first shows up to kill Riki-Oh, he brings a damn rocket launcher to do the job. Of course, considering that Riki-Oh survived being shot five times when he tried killing him in the backstory, this might count as being Dangerously Genre Savvy.
- Wife Husbandry: He had plans for this for the daughter of one of his underlings. Considering that said daughter would be turning 15 soon, this is extremely disturbing.
- Animal Motifs: He's often compared to a gorilla.
- Dumb Muscle: Subverted—while he's hardly a smart man, he's insightful enough to recognize that Riki-Oh's carrying a lot of grief beneath his grim demeanor, and pities him for it.
- Even Bad Men Love Their Mamas: He's shown to dote on his elderly mother.
- Even Evil Has Standards: Even when he was a full-on bad guy, he couldn't work directly under Mizuguchi after the crime lord orchestrated the mass murder of orphans and the homeless with poisoned food.
- Heel–Face Turn: Introduced as an Elite Mook for a low-level gangster, but chooses to follow Riki-Oh for the Mizuguchi arc.
- Heroic Sacrifice: When both he and Riki-Oh are mortally wounded by one of Mizuguchi's lieutenants, he chooses to give Riki-Oh a crude form of blood transfusion so that he might live...at the cost of his own life.
- Redemption Equals Death: Invokes this during his Heroic Sacrifice:Eisaku: I...I've done nothing but bad things my whole life...at least this way, I can die...like an honorable man...
- Stout Strength: He's got as much muscle as he does girth.
- Trademark Favorite Food: Bananas. Apparently, they make him even stronger in battle.
- Cold-Blooded Torture: He takes sadistic delight in tormenting his victims—in the backstory, he tortured Riki-Oh's adoptive father and grandfather; in the story proper, he punishes Mizuguchi rather savagely for failing to kill Riki-Oh in the backstory. Long story short, it involves a power drill, a hollow tube of bamboo, and boiling soy sauce.
- Creepy Crossdresser: Downplayed at first, with his penchant for nail polish and lip gloss. However, in the climax of his arc, he goes to wearing a full-out bridal kimono in honor of his deceased sister.
- Berserk Button: Don't do anything uncouth in his presence, like leave a hair in his tea. Or mention his true age.
- Depraved Homosexual: He has a creepy fascination with Riki-Oh at first. Later, this is lost beneath a hateful desire to see Riki-Oh dead.
- Disproportionate Retribution: His butler leaves a hair in his tea. Aneyama's response is to butcher him with a razor-edged ceiling fan. Later, when another of his servant's accidentally makes a remark about Aneyama's true age, the enraged villain kills him with another remote-controlled death trap.
- Driven to Suicide
- Even Evil Has Loved Ones: There is ONE human on the planet he cares about. His long-dead sister.
- Luke, I Am Your Father: He tried to pull this trick on Riki-Oh.
- Older Than They Look: He's in his 80s.
- Politically Incorrect Villain: He was a Nazi after all.
- Powered Armor: Used one during his fight with Riki-Oh to boost his strength. It looks suspiciously like RoboCop's armor.
- Sissy Villain
- Villainous Breakdown: He begins to steadily lose it when Riki-Oh begins tearing apart his operation. At the very end, he completely loses his head when his cosmetic surgery is destroyed, leaving him as an ugly old man, and throws himself off a cliff to his death.
- Those Wacky Nazis
- Bratty Half-Pint
- Disney Death: He's on death's door when Aneyama's "Crystal Night" plan goes into effect. Riki-Oh is guided by Nachi's spirit to use the power of his six-point-star hand to save the kid's life.
- Tag Along Kid: Notable, because he's the last of Riki-Oh's companions who follows him for the remainder of the story.
- Ace Pilot: He's able to fly his plane through regions that would cause lesser pilots to crash. This makes him a key ally to Riki-Oh, as Mukai's domain is in a part of the Arctic Circle that screws up the instruments of most planes.
- Badass Beard
- Crouching Moron, Hidden Badass: He comes off as a laid-back drunkard, but he's one of the best pilots in the sky.
- Jerk with a Heart of Gold: Abrasive and rough around the edges, but he's a nice guy once you get past that.
- Kindhearted Cat Lover: He has a pet cat named Sebastian
- The Ageless
- A God Am I: He seriously believes himself to be God.
- Bigger Bad: He's behind everything from the Cape arc onwards. All the other Big Bads beforehand were working for him.
- Dark Messiah: His most direct servants view him as a living god, and worship him devoutly. He was literally created to be this by the people of the future.
- Death Seeker: After Riki-Oh forgives him, Mukai is overcome with remorse. Unable to bring himself to kill his own son any longer, Mukai begs Riki-Oh to strike him down.
- Even Evil Has Loved Ones: It's implied that he did love Birei Oh, in his own messed-up way.
- Full-Frontal Assault: He confronts Riki-Oh in the nude in their first duel. Partly because he just finished bathing, and partly out of the "unconcerned with human expectations" variety.
- Luke, I Am Your Father: He is Riki-Oh's biological father.
- My Own Grandpa: Riki-Oh is his ancestor.
- Ki Attacks: He was able to use a Kantsu Reppa against Riki-Oh's to cause a Beam-O-War.
- Kid from the Future
- Nigh Invulnerable: Riki-Oh couldn't make a scratch on him, probably helps that he's immortal.
- Off with His Head!: And that still didn't kill him.
- Omnicidal Maniac: He wants to wipe out the human race because he thinks that is the only way to end their suffering.
- Villainous BSOD: When Riki-Oh shows him pity and forgiveness after hearing his story, Mukai breaks down in tears.