Rintarou Okabe, often nicknamed Okarin, is the main protagonist of the Steins;Gate anime and games.
Lab member 001 and the protagonist, an 18-year-old first year college student and leader of the Future Gadget Laboratory. Around a decade ago, in order to help Mayuri through a difficult situation he began styling himself as "Hououin Kyouma", an evil mad scientist, exasperating others with his chuunibyou antics. Despite his goofiness, he's actually pretty intelligent and has an intuitive grasp of much of what they're doing. He retains his memories when the past changes with complete clarity, an ability he calls the Reading Steiner.
Okabe has the characteristics of a lanky young man, with a square jaw and bony cheeks. He has his short black hair swept back and has brown irises, with a small amount of stubble on his chin. Rintaro also wears a lab coat, which he wears over a simple shirt and slacks.
In the game, Okabe appeared much "dustier". His face was pale and unshaven and he seemed a lot more "messy" in contrast to his relatively "clean" appearance in the anime.
Okabe is a melodramatic, eccentric and rarely tsundereindividual. He is a self-proclaimed mad scientist, who likes to assume the nickname "Kyouma Hououin" (Hououin Kyouma), and often uses this to introduce himself to others. For the most part, people do not seem to care and instead address him by his actual name or by 'Okarin' (his nickname), much to his chagrin. This makes him slightly hypocritical, due to the fact that there is essentially no-one he calls by their real names, and he in particular calls Kurisu a number of names that irritate her to varying degrees.
Okabe is also socially inept, to the point that he saw absolutely nothing wrong with yelling in Kurisu's face for calling him 'Okabe' instead of 'Hououin Kyouma' and couldn't understand why she was crying afterwards. Before that, he examined her body after discovering with shock that she was alive, which caused Kurisu to believe she was being groped by him practically the moment they met (in that timeline). His social skills are so poor, in fact, that Kurisu considers the childlike Mayuri to be normal by comparison. Although very intelligent, Okabe is shown to be easily deceived; when Kurisu sent him a D-Mail saying that he was an airhead, he bought her claim that it was a compliment, only realising later that it essentially meant his head was full of air.
Okabe likes to pose as an agent working against a certain "Organization" which he thinks is always after him, as he believes this kind of image gives him a cool and mysterious aura, though this seems to disappear as the story progresses, with SERN likely replacing the "Organization's" villainous image. He usually gives off the impression of being delusional and paranoid, engaging in strange mannerisms such as talking to himself on the phone and engaging in fits of maniacal laughter often; he seemed to have a severe case of Chuunibyou at the start of the series, but it is possible to realize that he is not delusional. There are several occasions, since the first episode, that the anime displays what goes on in his mind. In those moments the character reveals, by his thoughts, that he is very rational and concerned with the situations occurring around him and his friends.
It is later revealed that his 'mad scientist' persona is largely a facade he wears in order to make life interesting for his dear childhood friend Mayuri; after her grandmother's death, Mayuri fell into deep despair, but Okabe snapped her out of it by acting like a cartoon character and declaring her his hostage. He later drops his Chuunibyou facade upon witnessing Mayuri's multiple deaths, revealing a serious side of himself he has not shown for the first half of the series as he works hard to undo all the previous D-mails he has made, while in order to obtain the IBN 5100 and prevent Mayuri's death. As a result of going through dozens of time-leaps, he becomes rather cynical, depressed and frantic. He also develops a guilt complex, believing himself to be responsible for everything that's happening and frequently blaming himself whenever something goes wrong, even when he had no control over it or couldn't possibly have seen it coming. An example is when he blamed himself for stopping Suzuha from leaving during the night of the storm, which resulted in the loss of her memory and her failure in finding the IBN 5100, despite Suzuha's insistence that the entire thing was her fault for not going straight back to 1975 and instead stopping in 2010 to find her father.
In the Suzuha Ending (of the visual novel), Okabe's personality becomes exceedingly warped and twisted, as a result of being forced to choose between saving Suzuha or Mayuri. Despite this, he soon returns to acting like his old self upon being confronted by Suzuha. He has seemed to develop feelings for Kurisu, along with Faris, Luka, and Mayuri, although these are determined depending on the route chosen in the visual novel. However, he openly displays his affections for Kurisu near the end of the story, regardless of the route chosen.
- In the Gamma World Line, Rintaro is a collaborator of SERN, member of the Committee of 300 and becomes the dictator Hououin Kyouma, ruling over Japan with an iron fist.
- He loves to drink Dr. Pepper but in the Gamma world line, his favorite drink is Mountain Dew.
- The reason he barely calls Kurisu by her real name, but instead with the various nicknames, is because he was too embarassed to call her by her real name.
- The actions of the Committee of 300 of the Steins;Gate World Line fit Okabe's delusions almost to the letter.
- It is explained in the VN that his surname "Hououin" comes from the japanese equivalent to the mythical fire bird, the "Phoenix", which is pronounced as "Hou-ou". Kyouma comes from "Horrible truth" or something to that effect.
- He claims he has an IQ of 170. For reference, 145 is considered the genius level of intelligence.
- In 2015 December, "it was the choice of the voters (and the choice of Steins;Gate) that Okabe Rintaro is officially the Top Time Traveller." This bracket started on October 21st 2015, in which fans had till October 30th to submit time travellers for the bracket. Rounds of elimination between 64 different time travelers from popular culture occurred the following 6 weeks.
- MAGES. is a self proclaimed "mad magician" from Hyperdimension Neptunia, which is referencing Okabe Rintaro's "mad scientist". This character references Okabe Rintaro's character of loving Dr.Pepper. ("Doc Tear Popper") She even calls Noire "assistant" as Noire shares the same voice actress for Makise Kurisu, Asami Imai. There are sometimes references to a "Door of the Fate Stone" in which "Steins;Gate" literally translates into "Stone;Gate".
- During event 20 of Hyperdimension Neptunia Re;Birth 1 MAGES. takes out her cell phone and seemingly talks to herself about some kind of "Organization" getting rid of all of the Doc Tear Popper in the universe, this is a reference of Rintaro Okabe, who also does the same thing. She also ends her cell phone calls with "Loochs tneve emag noitamina cisum" claiming it is a secret code. Much like what Rintaro Okabe does. Only instead of "Loochs tneve emag noitamina cisum" he uses his own well know quote "El Psy Kongroo" (music, animation, game, event, school backwards, spelling MAGES.)
- Kurisu drank a can of alcoholic beer once, and was drunk before she could finish it, causing Okabe heaps of trouble. During the time she was drunk, she pushed Okabe downstairs and asked him to hug her and spend some quality time together. Okabe however, was too shy to even reply. Kurisu then hugs him even tighter and both of them fell down a flock of stairs, giving both of them a headache.
- In the future of the Alpha world line, Okabe became the leader of the resistance against SERN's rule, and was known as an international terrorist (in the side story ""The Distant Valhalla,"" it's revealed that SERN released Okabe and Daru so that they could found the resistance, thus completing the cycle of fate). Okabe got captured by SERN's Rounder unit in 2025 and was tortured to the point when his will to live is broken, and left braindead.
- In the events of Deja Vu, Makise Kurisu is the one who gives Okabe the backstory and name of Hououin Kyouma.