Steins;Gate

Suzuha bursts into the occupied laboratory and creates enough confusion for Kurisu to activate the time-leap machine. Okabe sends his memories to earlier that afternoon and awakens before the attack with full knowledge of Mayuri's murder. He forces the others out of the lab and searches desperately for a way to keep Mayuri safe. Kurisu quickly recognizes his changed behavior and infers that he has leaped through time. Okabe takes Mayuri toward the station, but the bomb threat has stopped the trains and Rounders close in. During their escape, Moeka strikes and kills Mayuri with a car. Okabe evades capture and leaps again, reaching an even earlier point. This time he guides Mayuri into the subway, only for Yugo's young daughter Nae to stumble and push her onto the tracks. Each altered plan changes the immediate cause but not the result. Okabe experiences Mayuri's death repeatedly while everyone else remains unaware of the previous attempts. Refusing to accept the pattern, he resolves to continue leaping backward until he finds a sequence in which she survives, regardless of the psychological cost of witnessing the same loss again and again.

Okabe repeats the same two days through successive time leaps, trying different routes, warnings, and hiding places. Mayuri dies in every version. From Moeka, he learns that SERN targets the lab because its members created a time machine and intended to reveal it. Exhaustion and accumulated grief finally overwhelm him. Kurisu notices that he is carrying knowledge no one else possesses and persuades him to explain. She supplies phrases and details that will convince her earlier self to cooperate after another leap. Returning to the period just before the time-leap machine is completed, Okabe recruits Kurisu and tells her about the apparently unavoidable deaths. Suzuha approaches them with the larger explanation: they are trapped within the Alpha attractor field, a cluster of world lines that converge on Mayuri's death and SERN's future rule. Saving her requires passing one percent divergence into the Beta attractor field rather than merely changing local circumstances. Suzuha leads them to the “satellite” embedded in Radio Kaikan and reveals it is her time machine. She is John Titor, a traveler from 2036 who came to alter the future Okabe has accidentally helped create.

Suzuha describes a 2036 ruled by SERN, whose successful time machine enabled a global dictatorship. Her original mission was to travel to 1975, secure an IBN 5100, and leave it where the laboratory could later use it to erase SERN's records. She stopped in 2010 to search for her father. When she attempts to depart, the machine malfunctions. Okabe realizes that the storm on the night he persuaded her to remain damaged it. He leaps back two days and assembles the lab members, assigning Daru to repair the machine while everyone else helps identify Suzuha's father from a distinctive pin badge. Suzuha gives Okabe the Divergence Meter, a device that displays the current world line, and tells him that his future self founded the resistance against SERN. The revelation replaces Okabe's playful claims of fighting a shadow organization with a real responsibility he never expected. The group searches Akihabara but finds only uncertain leads. Daru works against a deadline, because every delay risks Mayuri's death and the future Suzuha described. A badge maker finally provides information about the person who ordered a matching pin, giving Okabe one last chance to unite Suzuha with her father before she leaves for 1975.

Okabe time-leaps to question the badge maker's customer and discovers that the order came from Daru, who planned to create a replica simply to encourage Suzuha. Daru also explains that her damaged time machine can travel only into the past, so departure will be permanent. Once repairs are complete, Mayuri notices that the machine's initials match Daru's name and realizes he is Suzuha's father. Their brief reunion gives both of them the family connection they had been seeking across decades. Suzuha then leaves for 1975 to obtain the IBN 5100, but the Divergence Meter does not change. Yugo later delivers a letter she wrote in 2000. It reveals that the earlier storm damage caused her to crash, lose her memories for twenty-four years, fail the mission, and eventually take her own life. Blaming himself, Okabe sends a D-Mail preventing his past self from following Suzuha on the night she first tried to leave. In the revised world line, she departs before the storm and dies years later from illness rather than despair. The divergence value changes, but the correction also erases her reunion with Daru, forcing Okabe to trade one precious outcome for another.

Undoing the D-Mail that delayed Suzuha changes the world line, yet Mayuri still dies—only one day later. Kurisu concludes that the accumulated D-Mails keep the laboratory inside the Alpha attractor field. If Okabe reverses them in the opposite order, the IBN 5100 may return, allowing Daru to erase SERN's record of the first D-Mail and cross into Beta. The next message to undo belongs to Faris. While helping her escape angry Rai-Net competitors, Okabe describes the Akihabara that existed before her wish changed it. Faris begins recovering memories from the erased world line. Her D-Mail was a false kidnapping demand that convinced her father to miss a flight that later crashed. The ransom forced him to sell the IBN 5100, explaining why the computer disappeared. Restoring the old timeline means accepting his death. After he rescues them from the rival players, Faris chooses to send a counter-message despite the pain. Akihabara's maid cafés and anime culture return, and her father is once again gone. The IBN still does not reach the lab, confirming that each reversed wish is only one step in a chain and that Luka's message must be sacrificed next.

Okabe tells Luka that another world line exists in which he was born male and asks him to reverse the D-Mail that changed his sex. Luka initially believes the claim is another of Okabe's performances, but eventually accepts it on one condition: they must go on a date while Luka is still a girl. Kurisu and Daru offer elaborate advice, encouraging Okabe to behave like a conventional romantic partner. Their rehearsed outing becomes stiff and uncomfortable because both participants suppress the familiar way they normally interact. As the day continues, Luka begins remembering fragments of the previous world line and understands that reversing the message will also close the possibility of openly pursuing feelings for Okabe. Okabe realizes that treating Luka according to a role, rather than as the friend he knows, ruined their limited time. He returns to the shrine and practices sword forms with Luka as they always have. After an honest farewell to that version of their relationship, he sends the corrective D-Mail. Mayuri remains endangered, and Okabe must now confront Moeka, whose concealed message removed the IBN and whose future actions led directly to the laboratory attack.

Okabe visits Moeka's apartment and learns that she has taken her own life. He leaps backward and finds her alive but emotionally shattered because FB, the unseen handler who gave her purpose and ordered her to locate the IBN 5100, has stopped contacting her. Okabe seizes her phone and sends a message intended to cancel her original D-Mail, yet the world line does not change. He realizes Moeka lied about what she sent. Pressing her with knowledge of her future suicide, he uncovers the actual message: it revealed the computer's location and instructed her past self to retrieve it. A second corrective transmission still fails, because Moeka will obey only FB. To reverse the change, Okabe needs a message from FB's own phone telling her to abandon the mission. Feeling discarded by the person she regarded as her only connection, Moeka finally explains where the IBN was taken. Okabe's anger at her role in Mayuri's murder clashes with the recognition that this earlier Moeka is dependent, manipulated, and unaware of the bloodshed ahead. The search shifts from punishing her to identifying FB, the Rounder commander who controls both her actions and the missing computer's route to SERN.

Although Moeka identifies where the IBN 5100 was stored, Kurisu warns that stealing it could trigger another unpredictable change. Okabe, Kurisu, and Moeka instead watch the location and follow the computer as a chain of operatives passes it toward an airport. One of those couriers is Yugo Tennouji. Confronted at his home, he admits that he is FB, a Rounder forced into SERN's service under threats against his daughter Nae. He recruited vulnerable agents such as Moeka and discarded them after their assignments. Bound by the Rounders' rule for failed missions, Yugo shoots Moeka and then kills himself. Okabe uses Yugo's phone to send Moeka's past self an order canceling the search. The world line changes: both Yugo and Moeka are alive, and the IBN 5100 is once again in the Future Gadget Laboratory. Daru can finally enter SERN's database and remove the record that led the organization to them. As the solution comes within reach, Okabe recognizes its hidden price. Erasing the first D-Mail will return them to the Beta world line—the reality in which Mayuri survives, but Kurisu was found stabbed to death in Radio Kaikan.

Unable to accept saving Mayuri by restoring the world line where Kurisu dies, Okabe postpones deleting SERN's record. He cannot tell Kurisu why, so he accompanies Mayuri to a comic market while searching for an alternative that the attractor field has repeatedly denied him. At the predicted moment of Mayuri's death, a car approaches. Okabe tries to place himself in its path, but Mayuri pushes him away and is killed instead, proving that even exchanging his own life cannot defeat convergence. After another leap, Kurisu forces him to reveal the truth: crossing into Beta will erase the relationship they have built and return her to the day of her murder. Mayuri, meanwhile, visits her grandmother's grave. Okabe overhears her describe dreamlike memories of dying in many different ways and her awareness that he has been suffering alone to save her. Kurisu goes to Radio Kaikan, the place where she is destined to die, and considers the choice from her side. Okabe is left facing a decision that no further experiment has avoided: preserve Kurisu and continue Mayuri's endless deaths, or sacrifice Kurisu to restore the original divergence.

Kurisu tells Okabe that she has dreamed of being stabbed and of his repeated attempts to save Mayuri, suggesting that memories can echo across world lines. She insists that he choose Mayuri and return to Beta. Okabe refuses and prepares another time leap, but Kurisu stops him, warning that reliving Mayuri's deaths will destroy him before it changes fate. Accepting that no Alpha world line offers a third outcome, Okabe confesses that he loves Kurisu. She responds with a kiss and prepares to return to America. The next day, Daru uses the IBN 5100 to delete the first D-Mail from SERN's database. Kurisu races back to the laboratory to answer Okabe's confession, but the world shifts before she can finish. In Beta, Mayuri is alive, SERN never seizes the lab, and the Phone Microwave is dismantled. Kurisu is again dead, leaving Okabe as the only person who remembers their relationship. Some time later, Suzuha appears in a different time machine and asks for his help. In this future, SERN's dictatorship was avoided, but Kurisu's stolen research triggered a global time-machine arms race and World War III.

The Beta-world Suzuha explains that preventing Kurisu's death can lead to a world line called Steins Gate, where neither SERN's dictatorship nor World War III occurs. Okabe travels with her to the day of the Radio Kaikan seminar. He briefly crosses paths with Kurisu, creating the confusing encounter she mentioned when they first met, then hides near the room where she will die. Kurisu confronts her father, Doctor Nakabachi, who intends to steal her time-travel paper and claim it as his own. Okabe intervenes when Nakabachi attacks her, but during the struggle he accidentally drives the knife into Kurisu himself. Nakabachi escapes with the research that will reach Russia and ignite the future arms race. Horrified by causing the death he meant to prevent, Okabe returns to the present and refuses another attempt. Mayuri slaps him and reminds him that giving up contradicts the person he has always chosen to be. Suzuha then unlocks the scrambled video message from Okabe's future self. The plan is not to erase the events that inspired his journey, but to deceive his past self: Kurisu must survive while the younger Okabe still sees her apparently dead in a pool of blood.

Okabe prepares a second rescue using the future message's strategy. He first prevents a metal Upa toy from entering Nakabachi's document envelope, ensuring the stolen paper will burn during the later airplane fire rather than survive in a protective case. He carries a light-up sword whose liquid was meant to imitate Kurisu's blood, but discovers that it has dried. Inside Radio Kaikan, Okabe provokes Nakabachi into stabbing him and frightens him into fleeing with the research. He knocks Kurisu unconscious with a stun device and spreads his own blood beneath her, recreating the scene that his younger self must witness. The deception preserves every event that led to the laboratory's time-travel discoveries while changing Kurisu's actual fate. Okabe returns to a world line beyond the known attractor fields. Suzuha disappears because her future mission is no longer necessary. After recovering, Okabe distributes lab-member badges to the friends recruited across altered timelines and keeps one for Suzuha's eventual birth. He later encounters Kurisu on an Akihabara street. She does not consciously remember their erased relationship, but reacts to his familiar nickname for her, suggesting that some emotional trace crossed with them into Steins Gate.