Steins;Gate - episode 6 - 10 May, 2011

After dubbing messages sent to the past as "D-Mails," the group conduct further experiments, deducing the rules and limitations of sending D-Mails. Specifically, they learn when they can send one, how much data can be sent, and how far they can send them back. The next day, Moeka shows up at the lab to see the IBN 5100 and seeks to borrow it from Okabe. He tries and fails to hide the true nature of their experiments from her and so hails her as Lab Member No. 005. (Source: Wikipedia)