SaiTatsu

SaiTatsu is the het ship between Saitama and Tatsumaki from the One Punch Man fandom.

Manga
Tatsumaki and Saitama first saw each other when he arrived with Genos and Bang to the Hero Association’s S-class meeting. Before the meeting they were walking in the hall, and Tatsumaki questioned his presence in the HQ, calling him eyesore and wanting him to leave. Saitama then asks Genos what is with the “little lost child” and Genos tells him who Tatsumaki is. Then both Saitama and Genos ignore her when the other S-class have also come and gone to the meeting room. Tatsumaki didn’t like being ignored.

After Boros’ ship crashed and Saitama dealt with him, he comes out through the ship and Tatsumaki notices this. She then starts questioning why he was inside the ship, until she is being ignored again by Saitama and Genos. She gets angry and starts calling Saitama by names, which he doesn’t like. Then Saitama asks Genos to do something and he threatens Tatsumaki if she continues her childish behavior. With psychic powers she easily throws Genos to the nearby ruins of a building and tells him she is older than he is. Saitama is then surprised and worried about Genos. Tatsumaki stops her tantrum when Bang tells her to, and she leaves.

In Monster Association Arc Saitama learns from King that Genos protected Tatsumaki from the enemy, and he praises him for it. Then Saitama and King briefly check on Tatsumaki, as she is unconscious and injured from the fight.

Chapter 176 (online)
At the start of the Psychic Sisters Arc, Fubuki had brought Saitama with her Blizzard Group to the Hero Association HQ's special internment facility to meet with an inmate who she wants to talk with. As they arrive to the deep underground cell of the said inmate, who happened to be Psykos, they are met with the current visitors: a mysterious psychic guy from so called "Tsukuyomi" organization and the three Hero Association sponsors who were trying to sell Psykos to them, though the heroes are not aware of this inhumane act. As the HA sponsors are questioning Fubuki, Saitama and the Blizzard Group's reason to be there, Fubuki suddenly warns them about her sister, Tatsumaki, as she surely will come to finish off Psykos, because she was added to the official incarceration list by the HQ this morning and any pro hero can see it.

Suddenly the whole building starts to shake and the walls and ceiling starts to crack when Tatsumaki uses her psychic powers. Saitama realizes that it must be the one responsible for his apartment's destruction in Z-city during the fight against the Monster Association. Tatsumaki comes through the ceiling, appearing next to Psykos' unconscious body. She then tries to kill Psykos with a flick of her finger, but the mysterious psychic guy, as well as Fubuki, uses their own psychic powers to protect Psykos at the same time. Tatsumaki buries the "Tsukuyomi" guy to a nearby wall with her powers. Fubuki tells the sponsors to evacuate immediately while she and her group will hold off her sister. The sponsors start running towards the elevator in panic.

It's revealed that this whole act was planned by Tatsumaki, and Fubuki is simply secretly helping her sister protect Psykos from the psychic research organization Tsukuyomi. Tatsumaki has personal experience with them as her parents sold her to them when she was a child and they used her as their guinea pig in their research. However, no one else in the room, including Saitama and the Blizzard Group, know about the Psychic Sisters plan.

Soon the Tsukuyomi guy uses his own psychic powers to knock out the sponsors who were trying to flee the scene. He destroys all the surveillance cameras in the room, and then he gets himself out of the hole where he was buried on the wall. He tells the Psychic Sisters that they will make a nice additional souvenirs alonside Psykos. Tatsumaki is impressed that Tsukuyomi seems to have made a tiny bit of progress in creating artificial psychics. Fubuki notes that the guy is strong. Saitama ignores the tension and scolds Tatsumaki by telling her that he came to say a few choice words to the one who destroyed his home, but he now notices that Tatsumaki doesn't seem to have any sorry bone in her body. He then says that all the psychics can do is just demolish things.

This is ignored when Fubuki tells him that she is lucky he came along, which just confuses Saitama. Fubuki believes that Saitama was the one who defeated Garou in the end so he must be one who has "ascended", as was Garou during the Monster Association Arc. Saitama simply denies this as he doesn't have any recollections of defeating Garou.

However, Saitama soon falls to a chasm that was created when the Tsukuyomi guy's and Tatsumaki's psychic powers clashes against each other. Fubuki watches when Saitama falls to the chasm. The chasm closes up, leaving the Psychic Sisters, the Blizzard Group, unconscious HA sponsors and Psykos, and the Tsukuyomi guy on the scene. Saitama had fallen to the containment floor where all dangerous Demon-level monsters were kept.

Chapter 177-178 (online)
Tatsumaki shows her monstrous psychic powers and the Tsukuyomi guy notes that her telekinetic output is stronger than his. Tatsumaki adds insult to injury by asking did he really think he had any chance at his level and calls him a "poor little guinea pig". This doesn't sit well with the guy and he snaps his fingers which opens up the sleep medicine capsule inside Fubuki's body with his telekinetic signal. The guy then asks Tatsumaki threateningly if he should break the poison capsule next inside her sister's body. Tatsumaki realizes that it seems that there is a Tsukuyomi spy at either the manufacturer, the distributor or in the Blizzard Group, because the capsules were slipped in with Fubuki's daily beauty supplements. The Tsukuyomi guy then forces Tatsumaki to drop down her shield so Fubuki doesn't die from poison. He uses his own psychic powers to "pack up" Tatsumaki to a smaller "ball", bending her limbs unnaturally. Then the guy uses his psychic powers to break the Demon level containment floor door open to let the monsters kill all the remaining heroes and people, he then lifts the Psychic Sisters and Psykos with him. The spy from the Blizzard Group also reveals himself as he starts to leave with the other guy and the immobilized psychic women. The monsters then try to get free and the Blizzard Group is panicking.

Suddenly the monsters are all killed when Saitama jumps through them. This surprises everyone, including the Tsukuyomi guy and the spy. Soon also Tatsumaki finds the poison capsule inside Fubuki's body with her powers. Tatsumaki has to crush the capsule and its content inside her sister's body and turn it into a very thin needle that goes right through Fubuki's body and through the Tsukuyomi guy's hand to the eye. It injuries and poisons him, however he seems to be resistant enough as he is still alive. Furious Tatsumaki then uses the walls and ceiling materials to shut the guy inside a gigantic rock ball, threatening to "wring out" every piece of information about Tsukuyomi from him later. She also throws the spy on the nearby wall when he tried to escape. Tatsumaki then drops down with Fubuki, Psykos and the gigantic rock ball.

The Blizzard Group are all worried sick about Fubuki and ask questions about everything that happened as they did not have any idea about anything. Tatsumaki orders them all to shut up. She also tells Fubuki that she should cut all ties to her friends as the bad guys will most likely try to use her weak point again. The group tries to protest, asking Tatsumaki to give them another chance. They tell they can start taking measures against the enemy if they know more about the situation. Tatsumaki is mad and then threatens to cut their ties for them, killing them so that they won't die, but they won't work as heroes anymore. Fubuki protests this, but suddenly Saitama takes hold of Tatsumaki's arm, stopping her. She demands to know what he wants. Saitama says how both the sisters are so alike, though he then tells her that this is a bit too much just to lecture her sister. That heroes shouldn't beat each other up.

Tatsumaki demands that Saitama let go of her and Saitama tells her that she should then calm down. This doesn't sit well with her and she tells him to shut up and get out of her way, trying to push Saitama off her with her psychic powers, but it only manages to create a giant crater on the wall behind Saitama and he is a bit surprised that she tried to push him. However, Saitama then simply points out that it seems that is the psychic power that she used to sent Genos flying a while back. And that it doesn't seem to be that different from Fubuki. Tatsumaki is speechless and seems to be a bit surprised by his resistance, but is also not taking well by what Saitama said. Fubuki tries to warn Saitama by telling him that he shouldn't provoke her sister.

Tatsumaki then gets mad and demands again that Saitama let go of her. She pushes more with her telekinetic powers, but despite destroying more of the wall and the ground outside the facility, Saitama still holds on tight. As Tatsumaki tries to attack Saitama with her power, he starts to shake uncontrollably. He is surprised and asks why his muscles are twitching on their own like that. At the same time Tatsumaki is surprised and is wondering what is with this guy and how is he still enduring her attack.

Tatsumaki then realizes that she has seen him before with Demon Cyborg and asks him why is he involving himself with this and is he perhaps a part of the Blizzard Group too. Saitama doesn't seem to like that. He then yells Fubuki's name to gain her attention and tells her that he will take care of Tatsumaki while she takes everyone and evacuates. Tatsumaki gets interested in her sister's and Saitama's relationship. She says that Saitama is awfully familiar with Fubuki and asks if he isn't her underling then what is he to her. The question makes Saitama really think about it. He reveals that he doesn't consider her a friend, or a companion, or even a mutual friend, and finally tells that he is only her acquaintance.

The eldest of the psychic sisters doesn't buy this. She asks if Fubuki is just an acquaintance to Saitama then how come he is this "desperate". Tatsumaki then drops that subject and decides to try to test him and see if he is worth to be "hanging all over" Fubuki. Saitama doesn't like the implications, telling Tatsumaki that Fubuki is the one who drags him around without asking and is a "pain in the ass". Tatsumaki then pushes more of her telekinetic power around which causes the building to be in danger of collapse. Everyone inside the room and outside it are panicking, thinking the building is really collapsing under them. Saitama sees the destruction and shouts annoyed that Tatsumaki really treats people's houses like rags. He still keeps a hold on Tatsumaki's arm. She laughs and asks him loudly how long is he able to handle it.

However, to save the building from collapsing Saitama suddenly snatches Tatsumaki into his arms and she is clearly shocked by this. Saitama then jumps outside through the ceiling with Tatsumaki in his arms to deal with her.

The Murder Case That Is Too Impossible
The Murder Case That Is Too Impossible is the sixth OVA for One Punch Man anime series. Its story basically revolves around the “murder” of Zombieman as someone “killed” him by stabbing him with Atomic Samurai’s katana. Child Emperor begins investigating it.

In the end it’s shown that Tatsumaki stabbed him when she was really blackout drunk. Saitama asks Genos why Tatsumaki would do something like that. Genos knew the reason behind it, but doesn’t tell it. It’s revealed that the reason why Tatsumaki did overdrink like that was that Saitama said to her to not drink alcohol as she is still a child, which does make her feel humiliated (as she is actually older than Saitama). She takes revenge by drinking as much as she could from Saitama’s bottle of sake, resulting in her becoming very drunk and eventually stabbing Zombieman.

Webcomic
This section contains spoilers from the original webcomic version, which means that part of the information has not yet been adapted to the manga.

The main reason for TatsuSai ship’s existence is the webcomic, especially the Psychic Sisters Arc where Saitama stops Tatsumaki and Fubuki’s fight in the Hero Association’s HQ that had gone a bit too far. This leads to Tatsumaki and Saitama fighting each other, or rather her fighting Saitama who only takes on her attacks. Tatsumaki struggles to get rid of Saitama who keeps holding her tight, and he then jumps outside of A-city. There he still won’t let go of her, until they have a talk which leads to Saitama releasing his unwavering hold on her. But Tatsumaki then attacks Saitama, and Saitama keeps up with her powerful attacks. They keep calling each other names, and even have to protect a family car from each other that gets in their way during their fight.

Eventually Tatsumaki with her psychic powers pushes Saitama to a part of N-city, where the city’s most dangerous gang “Iron Fist” is located. A-class hero Feather is having some trouble with the gang as he was lured in by the gang’s boss’ girlfriend Erika, but suddenly Saitama goes through the wall and hits Feather, who is rendered unconscious. Saitama apologizes to the gang members and tells them that Tatsumaki will pay the repair cost. Then he realizes that there are already unconscious people on the ground, tells the gang that someone should call the ambulance and then blames Tatsumaki for it. She tells him that he was the one who flew into the building.

The Iron Fist gang didn’t like that S-class hero Tatsumaki appeared, and they try to attack her and Saitama. Tatsumaki just says how annoying this all is, and tells them she and Saitama were in the middle of something. They leave after dealing with the criminals that results into them saving both Feather and Erika, who in reality was doing everything against her will before.

Next in H-city there is a massive Dragon-level monster known as Kenzan Rat who was destroying the city. Metal Bat was assigned to deal with it, but when he arrived on the scene suddenly Tatsumaki and Saitama flew through the monster, killing it instantly and leaving a frustrated Metal Bat behind. Tatsumaki then continues to smash Saitama through the buildings and Saitama in frustration demands her to stop destroying everything. Then he says they need to go back as they have already gone too far from A-city borders. Tatsumaki suddenly agrees without any fight, which surprises Saitama as he mentions how easy that was.

Saitama then points forward and asks where was the Hero Association located. Tatsumaki takes hold of his head and tells him it’s the wrong direction, then she pushes his head face-first on the ground, tells him that she will help him get there, and starts dragging him through the ground with the help of her psychic powers. As she flies and drags Saitama’s head through the buildings, which doesn’t really affect him at all, Tatsumaki suddenly mentions that someone is chasing them. Saitama questions this, and Tatsumaki notes that the one chasing them is really fast. It’s then revealed that Speed-o’-Sound Sonic is chasing them after recognizing Saitama, but despite his attempt in catching them, Tatsumaki deals with him with his own explosive shuriken attack.

After a while they have returned to the borders of A-city. Saitama stops them there and tells Tatsumaki that they can now stop holding back. She seems to get angry at him and thinks he was looking down on her all this time. Then she starts to say that “if she went all out”, but before she can continue Saitama encourages her to go all out.

Tatsumaki goes all out and it leads to the Hero Association noticing this and the horrible tremors. Saitama even flies at one point to the hospital building’s wall and then goes back in to deal with the “Tornado of Terror”. When Tatsumaki notices that the attacks seem to have no effect on Saitama, she decides to lift him up with psychic powers and pull him to space. Unfortunately, she notices also that he seems to be really heavy for her to pull up and he seems to enjoy the floating.

Suddenly as she still tries to pull him up, something snaps in her and she feels sick. She drops Saitama on the ground as she can’t hold him anymore. Saitama asks her did she catch a cold, but she tells him to shut up. She then asks him why he hasn’t fought back at all even though she has put a lot of effort in it. Saitama smiles and tells her that just someone coming out and hitting her wouldn’t solve anything, and that he is here now for her to take on until she is tired. Then he would let Fubuki handle the rest.

This seems to be the wrong thing to say to her, as it only made her angrier, because Tatsumaki now thinks that Saitama truly thinks she will get tired before she can defeat him. Saitama notes that she does look tired already. Before Tatsumaki can do anything, she starts to bleed heavily. She is frustrated that her wounds she got during the Monster Association Arc has opened up. Saitama is worried when he realizes that she has been pushing herself even though she should be resting, and tells her that they should stop now and fight again when she is better. Tatsumaki agrees and tells him that they should settle this next time. She then asks his name and Saitama tells her with a smile. As she smiles back and says to him “Okay, Saitama. I’ll see you later”, she then suddenly opens up a massive and deep ravine under him and he drops in there. She then closes it up, and apologizes, believing also that Saitama won’t probably die from that.

She then looks at the Hero Association HQ in the distance and says aloud that she can’t pull back now and show Fubuki that she is weak. Fubuki then confronts her and soon Fubuki’s Blizzard Group follows also despite her wishes for them all to disband. As Tatsumaki is ready to attack them, she suddenly feels weak and drops to her knees. As Fubuki and her group are watching her, a giant tremor appears and Saitama’s head pops up from the ground. They all are surprised and confused, until Saitama says that “now you have done it” and starts digging through the ground towards them. They note how fast he is and he pushes up from the ground to face Tatsumaki seriously. He tells her he had forgotten his original objective and it was to confront the culprit who destroyed his home, and she has to settle things with him first. Tatsumaki then tells him that she doesn’t care and she doesn’t have anything to say to him, but she guesses that he won’t take that excuse.

Fubuki then stops them and tells Saitama that Tatsumaki hasn’t still recovered from the damage from the last battle, and if Tatsumaki continues to fight it could cost her life. Saitama then tells the Blizzard group that this could be nice chance for them to act if they want to pay her back, but they refuse as they understand it still wouldn’t make them stronger. In the end they promise to get stronger for Fubuki and for themselves. Tatsumaki then just decides to turn around and leave. Fubuki watches as she leaves and notices that Saitama also has disappeared.

Tatsumaki travels far with her psychic powers and drops down. Saitama suddenly is there and tells her she is already practically falling over and then asks can she make it back by herself. Tatsumaki is already so done with him and calls him a stubborn jerk, but then asks what he wants with her. Saitama tells her that he noticed she was bleeding heavily and was wondering if she was alright. She answers that of course she is alright. Tatsumaki then is leaving, and after few steps she stops and remarks that Saitama is strong, though if she was in perfect shape, she could flatten him in 5 seconds. Saitama only answers by saying “yeah, sure”.

She then asks does Saitama always hide his true strength, and calls him an asshole because of it, but Saitama tells her that he doesn’t try to hide it. Saitama does question her about the way she wants to cut off relationships with people and why she is a hero then. He first wonders if it’s because of income, but then seem to think it must be because she really wanted to connect with people as she seems to be bad at making friends. She looks at him and then yells at him to shut up for coming to his own conclusions, and then she bets that he doesn’t also have any friends. Even though Saitama tries to deny it she still hits a bit too close to home and calls him baldy. Saitama doesn’t like that nickname.

First Tatsumaki decides to tell him the real reason why she became a hero, but suddenly stops and decides that why she should tell him anything. She does however tell him that she is a hero, because it’s a stress relief for her and leaves it at that. Then she tells him to stop following her. After that she flies off, leaving Saitama to watch her leaving.

Fanon
SaiTatsu is a rarepair and has already a few fans within the fandom, thanks to the original webcomic and its Psychic Sisters Arc that brought a bit more interactions to this ship. In the webcomic they bicker at each other during their fight, though Saitama uses himself as a way for Tatsumaki to vent her feelings through destructive fight and tries to tire her out. Saitama also clearly shows a sign of worry when he witnesses Tatsumaki’s weakened state, and in the end wants to make sure she is fine. This shows fans that there is potential for this ship to become more.

However, the ship does have people in the fandom who don’t like the ship due to Saitama first thinking she was a child, because of her short stature, and because the manga has yet to explore their relationship deeper. It will most likely gain more fans when this particular story arc in webcomic is adapted to the manga, though due to some of the changes in manga it may differ a lot from the original version.

SaiTatsu rivals with ships such as Saibuki, Genosai and TatsuKing.

Fandom
FAN FICTION
 * Saitama/Tatsumaki tag on FanFiction.net
 * Saitama/Tatsumaki tag on FanFiction.net
 * Saitama/Tatsumaki tag on FanFiction.net

ART

TUMBLR

Trivia

 * Both Saitama and Tatsumaki are one of the most powerful heroes in their respective circles, and many people always waits for them to "finish the job" if no one else can do it. In that way they could understand each other if given the chance.