The central characters are:
Harry McQuinn (voiced by Ryu Itou): A shy and withdrawn teenager who one day discovers that he has powerful psychic abilities. Though he initially plans to his newfound talent to become famous, a series of horrifying events force him to flee as he desperately tries to keep these powers under control.
Catherine Chapman (voiced by Yui Horie): Harry's kindhearted classmate and pretty much the only person who is nice to him at the beginning of the story. Catherine initially encourages Harry to share his powers with the world, believing that this will help his self esteem. After things go horribly wrong, she resolves to protect him from The Accuser.
John Mayfield (voiced by Susumu Chiba): Catherine's wealthy boyfriend and a star athlete and student. He is the first to suspect that Harry may be at the center of some sort of sinister conspiracy, and resolves to help him out.
Mike Stafford (voiced by Nobuo Tanaka): A veteran police detective who first crosses paths with John and gets caught up in the conspiracy surrounding Harry while investigating a series of mysterious murders involving broken necks. After being placed on a forced vacation due to a cover up, he becomes an ally to the teenagers and tries to help them unravel the truth.
Kate (voiced by Yoko Soumi): A scientist who works for The Accuser, a clandestine organization dedicated to the study of psychics. She is tasked with capturing Harry for experimentation, but is also ordered to eliminate the boy if he proves to be a threat, something she becomes greatly conflicted about.
Ginori (voiced by Yukana): A mysterious psychic girl who befriends Harry during his escape from the Accuser facility. Despite supposedly wanting to help him, it quickly becomes clear that she has a ruthless streak and unknown ulterior motives.
The Fatman (voiced by Kôichi Nagano): A morbidly obese man who constantly spies on the main characters and manipulates them from the shadows, often sending them clues and teasing messages.
While the series was popular enough to warrant an anime, it is unfortunately rather obscure.
Sci-Fi HARRY provides examples of:
- Alone with the Psycho: Pretty much anyone who's unfortunate enough to be left alone with Ginori.
- Badass Long Coat: When outside, Kate is rarely seen without her stylish duster.
- Bare Your Midriff: Catherine, in spades.
- Bait-and-Switch Gunshot: At the end of Episode 6, Mick is about to shoot Harry in the head. The sound of a gunshot is heard, only for it to be revealed that Mike arrived in the nick of time and shot Mick before he could kill Harry.
- Bitch in Sheep's Clothing: Mischa first appears posing as an escaped prisoner who was supposedly being experimented on by Meryl. Harry only realizes too late that she was actually working for Meryl the whole time in order to trap him and get his genetic material.
- Blessed with Suck: Whenever Harry uses his powers, a nearby person dies of a sudden Neck Snap. The inciting incident of the series is when Harry seemingly causes dozens of accidental deaths while demonstrating his powers in front of a live studio audience.
- The Chessmaster: The Fatman.
- Clingy Jealous Girl: Mischa is heavily implied to be in love with Meryl, and acts extremely jealous when it's decided that Nadia will take her place in Meryl's experiment. This even applies to her body language, as she's often seen literally clinging to Meryl.
- Conveniently an Orphan: It's safe to say Harry is this. There's never even a reference to his parents, and he lives by himself in a crappy apartment.
- Creepy Child:
- To a lesser extent, there's Elliot, Catherine's little brother. He rarely speaks, often stares at the TV with a blank expression, and Catherine even compares his antisocial behavior to Harry's.
- Dead All Along: Mother was killed a long time ago in an experiment, but his consciousness survived and can communicate with Harry.
- Immortality Seeker: The Accuser, the organization that captured Harry.
- Also, Mother, though he now regrets getting it.
- And Ginori.
- Girl Next Door: Catherine, who is caring, kind and pretty much the only person who is genuinely nice to Harry at the beginning of the series.
- Hopeless with Tech: Being an older man, Mike is terrible with computers, and admits that they often frustrate him to the point where he wants to smash them.
- Invisible Parents: None of the central teenage characters have parents who are present in the series. Harry's folks are never seen or mentioned, Catherine pretty much raises her little brother on her own (her parents only appear in flashbacks) and Jonathan's parents don't even show up when he's in the hospital.
- It's All My Fault: Catherine blames herself for the incident at the TV studio, as she was the one who encouraged Harry to reveal his psychic abilities to the world.
- Loners Are Freaks: What most people think of Harry.
- Lovable Jock: Jonathan is the handsome star of the school basketball team, and one of Harry's few allies.
- The Men in Black: Early on, a pair of these show up to threaten John into dropping his investigation. Luckily Mike shows up to scare them off. After returning to spy on Catherine, it's revealed that they're agents of The Accuser.
- Mr. Exposition: The Fatman
- Old Cop, Young Cop: Middled-aged detective Mike Stafford and his young partner Bob. Bob doesn't survive past Episode 3.
- Parental Abandonment: Catherine's mother left when she was only a little girl, and her father is rarely home.
- Psychic Powers: Harry's telekinetic abilities.
- Sharing a Body: At the very end of the series, Harry and Chinori (whose body is already dying) appear to perish in an explosion. However, the final shot reveals that they survived and instead merged inside Harry's body, which now has long hair and Mismatched Eyes to signify the change.
- Spell My Name with an "S": English localizations can't quite agree on how to spell the name of the psychic girl who appears to Harry. Some call her "Ginori," while others go with "Chinori."
- Stalker with a Test Tube: Meryl tries to get Mischa and Harry to have sex in the belief that their combined DNA will hold the key to immortality. When it turns out that the two of them are genetically incompatible, she tries to combine Harry's DNA with that of Nadia.
- Unskilled, but Strong: Harry's just got his powers, and as such, he spends a large chunk of the show trying to get used to them. While he may not have that much control over them, when he manages to use them, someone or something is about to get wrecked.
- Who Wants to Live Forever?: Mother received immortality through experimentation, but was unable to handle it. He created Chinori to kill him, but this only succeeded in destroying his body while leaving his mind intact.
- You Have to Believe Me!: Jonathan is the first person to realize the deadly side effect of Harry's powers, but the cops don't believe him because he's only a teenager with an outlandish story, and Harry doesn't believe him because he thinks Jonathan is just jealous.