The Reading Steiner is a term referring to Rintaro Okabe's ability to, after switching world lines, retain his memory of events that have occurred (from his point of view) before the switch. In 1.382733β, this ability is referred to as President's Disease, as those with this ability remember Puchin as the President of Russia instead of General Secretary of the Soviet Union.
World lines can be switched by altering the past, for example through the use of D-mails.
While no other members of the cast have this immediate knowledge of a switch having occurred or any recollection of what happened in another World Line, they seem to regain fragments of these memories occasionally.
- Faris remembers sending the D-Mail that prevented her father's death after escaping the Viral Attackers with Okabe in 0.409431α.
- Lukako remembers her first meeting with Okabe as a male in 0.456914α.
- Mayuri, visiting her grandmother's grave in 0.571046α, remembers "Nightmares" in which she dies in a multitude of ways.
- Katsumi Nakase gains this ability during November 2010 in 1.129848β. Yuki pretends to have Reading Steiner to help her hide it in 1.382733β.
- Kurisu remembers some of her Alpha worldline memories in the Steins Gate worldline.
The ability plays a major role in the plot, most prominently in allowing Rintarou to undo the changes caused by the D-Mails and not losing track after each switch.
In the anime, there is a visual distortion every time a Reading is activated, usually following the sending of a D-mail.
- The movie Steins;Gate: Fuka Ryouiki no Deja Vu features the Reading Steiner as an important plot element, as Kurisu and Mayuri use recollection of the pre-Steins Gate world lines to piece together information about Rintarou.