Suzuha Amane

Suzuha Amane (阿万音鈴羽, Amane Suzuha), later known as Suzu Hashida, is a part-time employee for Yuugo Tennouji, the landlord of Rintarou's flat and is on a search for her father in Akihabara. She enjoys riding her bicycle and appears to be at odds with Kurisu.

She is in fact a time traveller from 2036 who, under the guise of John Titor, seeks to prevent SERN from creating a Time Machine that will lead to dystopia. Though she is unaware of it, she is the daughter of Hashida Itaru and Amane Yuki.

Radio Kaikan
At the start of the story, in the Beta World Line, Suzuha safely lands her time machine on the roof of the Radio Kaikan building. What happens afterwards is not shown as, shortly afterwards, the world line switches to the Alpha World Line in which the device's co-ordinates are slightly off, causing it to  "appear" inside Radio Kaikan's upper floor, damaging itself and the building. Regardless, Suzuha manages to acquire a MTB bike and a phone and seeks employment at the Braun Tube Workshop owned by Yuugo Tennouji in order to get close to the Future Gadget Laboratory.

Working Warrior
Rintarou first encounters her when she applies to work part-time at the Braun Tube Workshop. She appears fairly frequently but is often slacking off due to the Braun Tube Workshop's unpopularity. He christens her "Working Warrior", due to her statement that she is a soldier. She forms a close relationship with Nae Tennouji but always glares menacingly at Kurisu Makise whenever she sees her. She believes Kurisu is a SERN conspirator because she is hailed as the "Mother of Time Machines" in 2036, unaware of the fact that Kurisu's co-operation with SERN was probably involuntary. As John Titor, she exchanges mail with Rintarou and posts on @channel, although no-one is aware of her identity.

Search for Father
Suzuha attempts to meet her father at a time machine offline meet she knows he will attend. However, this meeting is prevented by an unknowing Rintarou, who prevents Daru from going to the meeting. Unable to meet her father, Suzuha leaves after sending a mail containing the single word "Goodbye" to Rintarou. She uses her time machine to leap to 1975 and obtain the IBN 5100. However, these events change after Rintarou sends a D-Mail so he would pursue Suzuha and prevent her from leaving. She remains in Akihabara, although during this time the time machine is damaged by rain water. Rintarou awards her the lab member no. 006 after accidentally telling her about the time machine's existence.

Last Supper
After the completion of the Time Leap Machine, Suzuha attends the celebratory dinner with the other lab members. However, she leaves after arguing with Kurisu. While she is gone, Moeka Kiryū and several Rounders attack the lab and kill Mayuri Shiina. However, Suzuha shows up and defeats all the Rounders. She is then trapped in a gun standoff with Moeka, giving Rintarou enough time to use the time leap machine to jump back in time.

Fate
(SPOILER ALERT)

Amnesia
After attaining World Line Divergence 0.337187% and using the Time Leap Machine to try and prevent Mayuri's death, Rintarou chooses to pursue Suzuha with both Daru and Mayuri, preventing her from leaving for 1975. her identity as a time traveller, John Titor and her search for her father are revealed. Using a pin belonging to her father, the group attempt to identify him, but are unsuccessful. Meanwhile, Daru attempts to fix the flooded time machine. After fixing the time machine, Suzuha prepares to leave to 1975 and obtain a IBN 5100, but Mayuri interrupts and reveals to the group that she has managed to work out that Amane's father is Daru. The two have an emotional "reunion" and Suzuha leaves in the time machine, sending Rintarou a mail containing only the word "Goodbye". However, Daru's repair was incomplete and the time machine malfunctions. Although Amane makes it to 1975, she is amnesiac and only remembers herself as "Hashida Suzu". She aids the young Yuugo Tennouji and acts as his mentor, but in 2000, her memories of 2010 return and she suffers a breakdown after realising that she failed to obtain the IBN 5100 despite meeting her father and sharing experiences with all the lab members. She writes a farewell letter to Rintarou, telling him of her tragic fate, and entrusts it to Yuugo, who gives it to him in 2010. After writing the letter, Suzuha hangs herself.

Suzuha's Ending
In this world line, the events of World Line Divergence 0.337187% recur endlessly due to Rintarou being unable to decide between saving Suzuha or Mayuri, so he loops time endlessly for himself by using the time leap machine to re-live the two days Suzuha spends with the lab members endlessly. However, after possibly hundreds or thousands of loops, Suzuha realises time is looping and confronts Rintarou. After discovering the truth of her suicide, she asks him to come with her to 1975 to ensure that she will not hang herself and will secure an IBN 5100. Rintarou's emotions begin to revive after this. The two enter the time machine and travel to the past, but what happens to them is not revealed.

1975
After Rintarou prevents himself from stopping Amane from leaving after her failed meeting with Daru, she leaves in the unbroken time machine and her memories remain intact after the journey. She secures an IBN 5100 and mentors Yuugo Tennouji under the name "Hashida Suzu" (which suggests that she figured out that Daru was her father, despite not meeting him before travelling through time). However, she becomes terminally ill at the age of 54 and dies in 2000 of natural causes. Her Divergence Meter passes into Yuugo's possession. Unlike in World Line Diverence 0.337187%, she does not die in anguish and accomplishes her mission, passing on the IBN 5100 to Yukitaka Akiha.

Beta World Line
In the Beta world line, World War III breaks out. Daru invents a complete time machine that can travel backwards and forwards in time, which Suzuha uses to travel to 1975 and 2000 to secure the IBN 5100 before travelling to 2010 to save Makise Kurisu and change the past. This Suzuha is aware Daru is her father. Her personality is slightly different from Alpha world line Suzuha. She and Rintarou travel back to July 28, 2010 to save Kurisu. After securing Kurisu's life and faking her death to trick the past Rintarou, Suzuha disappears, as in the rebuilt future, Daru's time machine was not invented and she did not travel back to 2010.

Robotics;Notes
After the events of Steins;Gate, in Robotics;Notes it is revealed that Daru got married and has a daughter, who may be the Steins;Gate world line's version of Suzuha. However, she doesn't appear during the events of Robotics;Notes.

Trivia

 * Suzuha's voice actress, Yukari Tamura, also voices her mother.
 * Suzuha made an appearance in Steins;Gate: Hiyoku Renri no Darling as one of the main possible romantic interests of Rintarou. Her existence in this world line is odd, since the setting of this visual novel took place in a world line where SERN's influence is almost non-existent, the creation of the Phone Microwave did not happen and time-travelling technology was never (and is highly unlikely to ever be) developed, Suzuha would have absolutely no reason (and no way) to appear in 2010.