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.

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 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.