|Romaji Translation:||Sonzai Ryōkai no Meruto|
|Release Date:||August 31, 2011|
|Opening Song:||Hacking to the Gate|
|Ending Song:||Toki Tsukasadoru Juuni no Meiyaku|
|Previous:||Episode 21: Paradox Meltdown|
|Next:||Episode 23: Open the Steins Gate and SG0 OVA: Episode 23(β) Open the Missing Link|
Okabe and Makise find themselves faced with the unthinkable: saying goodbye before their time together had really even begun. Will they admit their true feelings before it's too late?
Kurisu now sprawls herself on the roof the same way Okabe did, albeit on the radio building roof. Okabe finds her there, and they briefly mention Mayuri when Kurisu tries to say something else, only to stop herself. From there it starts to rain, causing them to both get soaking wet. They try drying off inside the building, where Kurisu's wet clothes end up exposing her body beneath her clothes, to Okabe's surprise. They quickly begin arguing about it when Kurisu notes that Okabe has torn his lab coat on the shoulder. As she has a sewing kit, Kurisu offers to stitch it. Since it was dark there she was unsure the color of thread she used, either black, red, or pink. As Okabe reluctantly has her do so, Kurisu asks where he tore it. Okabe doesn't know, but does retrace his steps, revealing that, since Kurisu didn't answer her phone or anything, he became worried and went around the city, including her hotel room, looking for her; this causes Kurisu to smile. Kurisu then tosses the lab coat onto Okabe, saying that no one wants to see a mad scientist with pudding for a brain; of course, Okabe puts the coat on, and discovers to his chagrin that Kurisu used the pink thread. Kurisu then stands up and asks if she dies in the building. Okabe, shocked, asks if she remembers her death. Instead, Kurisu says that she only has partial memories of it all, and it's like she's having a hazy out-of-body experience. She then says she also remembers Okabe constantly chasing after Mayuri, constantly suffering because she is irreplaceable. Acknowledging that no one has ever felt like that about her, Kurisu asks for Okabe to go back to the world line, even if it means her death, because there is no other way.
Okabe refuses, and heads back to the lab, determined to find a way to save both of them. When he gets there, he prepares to time leap again, but Kurisu catches up to him and stops him before he can, telling him that she wants the D-mail to be erased. Okabe grunts to himself, and Kurisu continues that time leaping won't break the 1% barrier, and that watching Mayuri die too often will eventually shatter him. Okabe says that isn't the case, because he has already Mayuri die dozens of times. This prompts Kurisu to slap him and say that, if Mayuri dying doesn't harm him anymore, than his heart is already broken. Okabe concedes that she may be right, since Mayuri dying has become numb to him, so he might as well just let it go. Kurisu argues that, if he just lets her go after working so hard, he will break even further. Okabe continues to argue what will happen, but Kurisu says that this is for the best.
Overwhelmed, Okabe hugs Kurisu. In his head, he finally realizes that, out of all the people he knew, Kurisu was the one who, despite constantly bickering with him, always shared problems with him and believed in him, her theories are always fantastic, he remembers every single word she has said, and the reason why he never calls her by her name in normal situation is because he was embarassed to do so, but he never told her what he truly felt. In reality, Kurisu shrugs at the thought of someone wanting her around so much. Okabe, however, goes over to the window and questions why it had to be her. Kurisu tries to cheer him up, telling him that, in the end, there are infinite universes, many with their own version of her. And having been in many of those universes, Okabe can formulate Kurisu from the dozens of Kurisus he met, and to that end, she won't truly die as long as he remembers her. After some time, Okabe says that he could never forget about her, the person he cares for more than anyone, even if he tried, and proceeds to confess love to her, much to her surprise. He then asks Kurisu what her opinion is, at least that very moment. In response, Kurisu tells him to close his eyes, and after he does, Kurisu pulls him slightly downwards and kisses him. After a long period of time, Kurisu breaks the kiss and quickly tries to ride it off by saying that she only did it under the assumption that it was his first kiss and therefore would remember it better since it's stored in the hippocampus. Okabe promptly says that that wasn't his first kiss, but that the first one wasn't romantic. To that end and to avoid the hippocampus forgetting the kiss, he asks for another kiss. This results in them passionately kissing. As they do, Kurisu thinks to herself that time is flying by, implying that she likes the kisses, and that Einstein's theory of relativity must be true, as well as both romantic and tragic. But in the end, Okabe doesn't know how she feel about him.
The next day, Kurisu prepares to head back to America. Okabe sees her off at the train station, and gives her his Future Gadget #2 Bamboo-copter camera as a memento, even though she doesn't want it. As she prepares to leave, Kurisu throws him a soda bottle; it ends up going over his head, forcing him to go get it. As Okabe reaches down to pick it up, Kurisu mouths something to him, but when Okabe looks back at her, she has already left. Kurisu, while waiting for the train, thinks to herself that Okabe will have it rough since, out of all the lab members, only he will remember her, and he will have to shoulder that burden alone. She then concedes that he cares about people more than he lets on, and that she wants him to remember her every once in a while, even if he kisses someone. She then begins repeating Okabe's name over and over again in her head.
Okabe returns to the lab, where Daru hacks back into SERN and finds the first D-mail. As they prepare to delete it, Okabe clutches his head. Mayuri asks him if he is okay, and Okabe quickly goes into another rant, saying that he has finally defeated the Organization and thanks them all for working so hard to strive for victory, but begins to tense up when thinking of the blood that had to be shed. Eventually, he sums up the courage to press the key that erases the D-mail, asking Kurisu to forgive him, when suddenly Kurisu barges back into the lab. Panting, she looks at Okabe and tries to say that she loves him, but Reading Steiner kicks in.
Okabe finds himself in the position he was in after introducing his lab members. After confirming that Dr. Nakabachi's press conference is accomplished, he asks Mayuri about labmem number 004, and learns that no one remembers Kurisu. Going into hysterics, Okabe claims he has finally triumphed and that he can look to the future. However, Mayuri reveals that she is alright now, and tells Okabe that he can cry if he wants. Afterwards, Okabe ships away all of his lab equipment to avoid any more risks, and asks Kurisu if this is for the best.
However, during the end of the credits, Daru gets a call from someone who claims to have some relation to him, and asks to talk to Okabe. As Okabe picks up the phone, he discovers that the person is Suzuha, who says that the future is still in disaster, and demands that he come to the rooftop of radio building to help her prevent World War III.