Itaru Hashida/Plot

Steins;Gate
While Rintaro Okabe and Mayuri Shiina are off to attend Dr. Nakabachi's seminar on time travel, Itaru stays in the lab to try to find out what the problem with the PhoneWave (name subject to change) was, the lab's latest Future Gadget. As he experiments with it, a message from Okabe, informing him of the murder of Kurisu Makise arrived and is sent to the past through the PhoneWave, shifting the world line towards the Alpha Attractor Field.

Alpha Attractor Field
On the Alpha Attractor Field, Itaru's phone had received an odd message from Okabe a week prior, containing only part of the message Okabe had sent to him on the Beta world line the same day.

He helps Rintaro Okabe grasp the mechanism of the PhoneWave (name subject to change) better by hacking into SERN for days, which results in him, Okabe and Kurisu Makise finding out that SERN has been conducting time travel experiments by using hundres of human subjects for nine years (since 2001). Later, he attempts to attend an offline meeting about time travelling, the same one Suzuha Amane was going to attend, but is stopped by Okabe to help out with the party for Suzuha. On another world line, to cheer up Suzuha in case they could not find her father, he planned on forging her father's metal pin and lie to her that he had received it from her father. Okabe time leaps back to prevent this. On this world line, Itaru attempts to fix Suzuha's broken time machine instead, but Suzuha becomes amnesiac after using the faulty time machine to travel to 1975 which made her commit suicide in 2001. When he finds out that he is her dad right before sending Suzuha off with the others, he promptly reacts with perverted comments but soon becomes awkward and emotional at seeing his future daughter. When Okabe sends a D-Mail to himself in the past so that Suzuha can use the time machine before the rainstorm, Itaru forgets that he is her father.

Irreversible Reboot (Suzuha ending)
On Okabe's countless time leaps to stall for time, Itaru follows along with Suzuha, Okabe, Kurisu and Mayuri on their cycling session, but struggles to keep up and complains the whole way. He stops once to rest on a guardrail and is almost hit by a truck every time (depending on the time leap, Okabe pulls him away from the guardrail). They then arrive at Big Sight (where ComiMa is held) and Itaru is excited at finally being at their destination point. He then proceeds to look for a family restaurant with Kurisu and Mayuri. On the very last world line in the time loop, Itaru finishes the time machine and is called to a Future Gadget Lab meeting by Okabe. On these world lines, Itaru does not know that Suzuha is his daughter.

Steins;Gate 0
During the events of Steins;Gate 0 on the Beta Attractor Field, Itaru helped Maho Hiyajo with building a new Time Leap Machine and often helped retrieve Amadeus' data by hacking. He also recommended Moeka Kiryu to Okabe when they needed someone who could find Kagari Shiina. He was contracted by someone anonymous, later revealed to be Maho, to hack into Kurisu Makise's laptop.

Pandora's Box
Maho takes Okabe to the anonymous hacker she had contracted, and hence took him to Itaru's secret hideout. Itaru is surprised that his contractor was Maho all along and also at seeing Okabe. Okabe tells him that he should stop trying to hack into the laptop. They then get a call from Amadeus [Kurisu]. Depending on if Okabe picks it up or not, the story leads into a different route.

Gehenna's Stigma
Okabe picks up the call. Amadeus tells them that someone had raided the office in Wako City and Maho's room. As they realise that this someone was after the laptop, they see several men beginning to surround the building through security cameras. Itaru leads them through his secret exit and they manage to get out from the back of the building. Shocked, they escape just in time.

Presage or Recognize
Okabe does not pick up the call. Itaru shows them the laptop and the hard drive. Okabe, Itaru and Maho bicker and Itaru advises Okabe to tell Maho about the time machine and time travelling. Okabe suggests destroying the laptop to which Itaru protests that he was nearly done with it and that he would not get his pay, which he had used some of already. They get interrupted by a beep from the security monitor that alerts them that multiple men have surrounded and infiltrated the building. They leave through Itaru's secret exit but become cornered in an alley with Maho getting captured. At Okabe's demand the one holding Maho takes off their helmet and reveales themself to be Moeka Kiryu to their shock. Okabe instructs Itaru to give him the backpack containing Kurisu's laptop, which he would then give Moeka in exchange for Maho. Okabe tries stalling for time which makes the Rounders impatient and Moeka threaten to kill one of them. Suddenly, a black van pulls up at the end of the alley from which multiple armed people jump out and start shooting at the assailants. Okabe, Itaru and Maho manage to duck out of the way just in time. In the gunfire the laptop is destroyed. The Rounders flee, the armed men take what remains of the laptop with them and Okabe, Itaru and Maho get back to the lab, all being shaken.