Itaru Hashida, almost universally called by his nickname Daru, is a central figure in the Future Gadget Laboratory as its third member. He is a first-year student at Tokyo Denki University and carries himself with the physical build of a short, overweight young man who typically wears glasses, a simple dark green t-shirt, blue jeans, and his signature yellow cap. His personality is defined by a striking contrast between his technical genius and his pronounced otaku lifestyle. Daru is an exceptionally gifted programmer and hacker, operating online under the alias DaSH, which stands for Daru the Super Hacker. He has a fervent obsession with moe culture and anime, often making perverted remarks and proudly calling himself a "perverted gentleman". Despite his lazy and lecherous exterior, Daru is a dependable and loyal friend, acting as a grounding presence for the more eccentric members of the lab. He is acutely self-aware of how others perceive him, particularly feeling insecure about his appearance and personality when interacting with women he truly cares about, such as his future wife, Yuki Amane.

Within the story of Steins;Gate: The Movie - Load Region of Déjà Vu, which takes place one year after the original series, Daru's role shifts slightly as he has effectively become the founder and primary maintainer of the Future Gadget Laboratory. With Rintaro Okabe struggling psychologically, Daru steps up to keep the lab operational, often seen at his computer working on various projects. His primary motivation in the film is unchanged from the series: supporting his friends. He is instrumental in the background, using his extraordinary hacking abilities to infiltrate high-security systems like SERN for purposes that even he cannot fully remember, a consequence of the timeline's instability. His actions provide a crucial technical foundation for the events to unfold, even when he is not consciously aware of the full scope of the temporal crisis.

Daru's key relationships define his character. His bond with Rintaro Okabe is foundational; Okabe considers him his best friend and "my favorite right arm," a trust that holds true in the movie as Daru continues to support him. His relationship with Kurisu Makise is one of sharp-tongued camaraderie, as she is often the one to quickly rebuke his perverted comments. A relationship that casts a long shadow over his entire life is with Suzuha Amane, the time-traveling soldier who is, in all worldlines, his future daughter. While his interactions with her are often awkward and filled with his usual immature jokes, it masks a deep-seated care and a complicated future that awaits him. In terms of development, the movie does not show a radical transformation for Daru, but rather reinforces his role as a stable, reliable force. While others are losing their grip on reality, his steady presence and technical contributions remain a constant, anchoring the lab in the present despite the chaos.

Daru's most notable ability is his unparalleled skill as a super hacker. He can breach the mainframes of world-class research organizations with ease, a talent that is the backbone of many of the lab's achievements and a key plot device in the film. Beyond programming, he possesses strong hardware skills, helping to build and repair the various gadgets dreamed up by the lab, including the Phone Microwave. While his outward demeanor is often comedic, his genius-level intellect and steadfast loyalty make him an indispensable part of the team, without whom the events of both the series and the movie would not be possible.