|Name in Japanese||自己相似のアンドロギュノス|
|Romaji Translation||Jiko Sōji no Andorogyunosu|
|Release Date||August 3, 2011|
|Episode Director||Kazuhiro Ozawa|
|Previous||Episode 17: Made in Complex|
|Next||Episode 19: Endless Apoptosis|
Ruka is up next on the list of D-Mails to erase, but before she's willing to surrender her femininity, Okabe must agree to be her boyfriend for a day!
Okabe goes to meet Ruka and tries to get her to regain her memories by telling her that she was a male at one point. Instead, Ruka begins slightly crying, so Okabe tells her about Mayuri and asks her to give up being female.
August 13th, 2010: 3:31 PM
At the lab, Okabe sits solemnly on the sofa. This provokes Kurisu to joke that he looks so down all of a sudden, much to his chagrin. Mayuri then comes in and shouts at Okabe for making Ruka cry, having invited her to come to the lab only for her to burst into tears over Okabe's "comment". Kurisu promptly gets on his case, so Okabe takes her to the park and explains the entire situation. Kurisu initially doesn't believe it, but does when she realizes that the next scenario might be Daru looking like her. She then suggests that, since Okabe knows what the text said, he can undo it himself since Ruka wouldn't possibly want to go back to being a boy, but Okabe says that he doesn't know the pager's number and would rather not be so underhanded. Kurisu then says that the real reason Ruka doesn't want to go back is because she has a crush on Okabe. However, just then, Ruka sends Okabe a text asking him to come to the shrine.
When Okabe gets there, Ruka tells Okabe that she believes him, but asks him a favor: before sending the D-mail, they have to go on a date the following day. Despite Okabe's dismay, he agrees in order for Ruka not to cry. Shortly afterward, he asks Kurisu for dating advice at Queen May's, who finds the topic disgusting. Okabe then admits that he is throwing caution to the wind by asking his assistant for dating advice but to not taunt him, and Kurisu again complains about the assistant label. This causes Faris to notice, and she asks who with (even suggesting it's Kurisu), before saying that "all this women chasing" will tamper with his "special technique". This leads to a innuendo-riddled debate between Okabe and Kurisu, which Daru ends up overhearing. At the lab, he tries to give Okabe dating advice by talking about all the girls he made out with on his online harem, but Okabe brushes him off. Okabe then tries to look up places to go out at, but concedes. This leads to a conversation between him and Kurisu over their virginity, during which Kurisu accidentally reveals she is also a virgin.
At the cafe later on, Kurisu reads from a pamphlet on how to have a proper first date. Based on what she reads, Okabe suggests wearing his lab coat and going to Queen May's, but Kurisu tells him to lose the coat and go somewhere else, leading to another argument; Daru then tries to get Okabe to read a hentai game strategy guide for advice before leaving. They end up debating ideas until the morning, at which point Kurisu forces Okabe into a suit. She then forces Daru to help her spy on Okabe so he doesn't screw something up. Eventually, Okabe goes to wait for Ruka on a bridge, and after meeting her there, they head off. While walking down the street, Okabe keeps on playing various scenarios and how to react to them in his head, leading to some awkward but well-intentioned moments, to Kurisu's frustration. They eventually come to the restaurant, where they struggle heavily with small talk. From there they start walking again, during which Mayuri notices them. After passing under a bridge, Ruka asks Okabe if he remembers when they first met: not long prior, several boys began taking pictures of him under the assumption that he was a girl, and Okabe brushed them off; when Ruka said that it hurts to always be mistaken for another gender, Okabe replied that she should just be herself, causing him to fall for him. This causes Okabe to realize that Ruka now has partial memories of her male world lines, just like with Faris.
Okabe takes Ruka back home that evening, where Ruka thanks him by saying that the date meant everything to her. She then gives her the pager number and runs off. Daru and Kurisu write the D-mail, but Okabe seems down. Mayuri then comes in and notes that Ruka was on a date, but didn't recognize Okabe due to his clothes. This causes Okabe to realize that he didn't give Ruka the date she deserved, promptly running back there in his lab coat and doing activities that they normally do well into the night. After it's done, Ruka tells Okabe that, when she was younger, she knocked over the IBN 5100 and it broke, and because of that the current situation happened. She then bids a disappointed Okabe goodbye, but then suddenly hugs him from behind. She then cries and says that she doesn't really want to be a boy because to her, homosexuality is taboo, and she won't remember the day. Okabe promises that he won't forget it, and that will be enough.
The D-mail is then sent, leading to the divergence meter raising again. Okabe finds Ruka carrying logs, and asks if he likes him, but she tries to hide it, making Okabe realize it worked. Okabe then plans to send the last D-mail.