Luka Urushibara

Luka Urushibara (漆原るか) is a close friend of Mayuri Shiina and so-called protégé of Rintarou Okabe. While feminine in appearance and personality, Luka is a male. Mayuri is his classmate, who often attempts to coerce him into cosplaying (without much success).

Appearance & Personality
Although being biologically male, Luka has an extremely feminine appearance, causing him much trouble (and attention) from men (even Daru was at one point attracted to Luka's appearance). He is very slim, with thin arms and lanky body.

Luka have always dreamed of being a complete girl, and was disappointed that he was born a male. This changes later on, as Luka was turned into a female through the influence of a D-mail, though the female Luka does not remember being male before.

He is very sensitive and emotional, as simple sudden responses from Rintarou can cause him to cry or tremble. He likes to wear girly clothing, which caused Kurisu to confuse him for a real girl when the two met in Rintarou's lab. Rintarou even described him as "more girly than any girl, more feminine than any female" in the game.

Luka harbors deep feelings for Rintarou, ever since their first encounter in Akihabara, when he was still a male. Luka knew this feelings were illegal, but he hide it anyway. Later in the story, as Rintarou attempts to save Mayuri by reversing the effects of sent D-mails, the female Luka tearfully agreed under the condition of Rintarou taking her out on a date. The date turned out awkwardly, since Rintarou was unable to be himself around her. He came to see her at the shrine and apologizes for botching the date, and the two embrace. Luka said she would still love him even if she's no longer female.

Plot
Luka was first introduced as an extremely feminine individual. Okabe expressed his confusion over this matter quite a few times throughout the game, and at the near beginning of the anime.

After learning of the existence of SERN and the IBN 5100 personal computer, Rintarou discovered it being stored at Luka's family's shrine. In the alternate worldline Luka accidentally broke it when he/she was cleaning the storehouse.

Being told of Rintarou's experiments, Luka tells the Future Gadget Lab members a Japanese urban legend: if a pregnant woman eats more meat during her pregnancy, then her baby will be a boy, and if she eats more vegetables, her baby will be a girl. The Future Gadget Lab, although skeptical of whether or not the urban legend is true, lets Luka send a D-mail back to his pregnant mother's pager, telling her to eat more vegetables. In episode 10, it's revealed that the D-mail has worked and the characters are transferred to a world line where Luka becomes Lukako. ("-ko" is a common ending exclusive to female names, and therefore, would mean in that world line, Luka has become a biological girl.) This causes an extremely awkward situation in which Okabe does not realize this and gropes Lukako's crotch in order to prove to the Future Gadget Lab that Lukako is male. He quickly learns that he's been moved to a world line where Lukako is a girl and that he's been accidentally sexually harassing her while causing Lukako heavy embarrassment.

Later, when Rintarou attempts to achieve 1% divergence, he was troubled by the thought of reversing Luka's wish. Luka agreed to it, though reluctantly, after confessing her love for him and requests that he takes her out on a date. The date turned out awkwardly, since Rintarou was unable to be himself around her. He came to see her at the shrine and apologizes for botching the date, and the two embrace. Luka then spends the rest of the day practicing with the sword Samidare along with Rintarou; both of them feeling genuinely comfortable in each other's company.

Luka was revealed to have been in love with Rintarou since their first encounter (when Luka was a male) and that she will still love him no matter what happens, female or not. Rintarou smiles and sends the D-mail, reverting Luka back to being a male.

In the game, Rintarou decides not to send the mail, but helps Luka time leap back to join Mayuri at her last cosplay convention. They would then continue to live on as lovers.

Luka's Ending
In this world line, Rintarou decides not to send the D-mail that would make Luka return to being a boy again. He convinces himself that Mayuri will still die no matter what he does and he doesn't want to sacrifice Lukako's happiness. Lukako confesses to Rintarou and swears to give him her mother's pager number on the condition that the two go on a date together once. The two's date is deeply awkward and contrived, so much that Lukako cuts it off abruptly, leaving Rintarou to guilt over it. He realizes that it wasn't truly a date because he was trying too hard to impress her by not being himself, and rushes over to the shrine where the two spend genuine bonding time together. After which, Lukako gives Rintarou her mother's pager number in order to send multiple D-mails to Lukako's pregnant mother. This will cause Lukako's mother to believe that all the D-mails (including the original one sent by Lukako) to be spam, ignores them, and continuing on eating more meat, and thus giving birth to a male Luka. Because Rintarou doesn't want to turn Lukako back into a boy, he doesn't want to wipe out any memories anymore, the timeline goes on and Mayuri still dies. Realizing the devastation she has wrought, Luka feels guilty about Mayuri's death. Remembering that Mayuri wanted Lukako to cosplay in the next convention, Lukako with the help of Rintarou, leap back in time to give Mayuri at least some happiness. The plan was a success, as in that timeline Lukako, Mayuri and Rintarou went to the convention together but left Mayuri's fate ultimately unchanged. The scene closes with Luka producing the pictures they took together with Mayuri at the convention; with Rintarou at peace now that he has given Mayuri some happiness. After the credits, Rintarou is shown to have fathered a child with Luka.

Quotes

 * "If I go back to becoming a guy, I'm going to forget all about today, that the two of us went on a date, that the two of us trained, that I was able to touch you this way...If I knew I had to suffer like this, I would never have wished to become a girl..."

Trivia

 * Though being feminine, Luka would always use the term "boku" to address him/herself. "boku" is the male form of addressing oneself in Japanese, so it is strange that a person like Luka would use it.
 * Luka has an older sister in college who, according to Luka, is the polar opposite (in terms of gender attraction) of him. Though she is only mentioned in the game.
 * Though referred to as Lukako in the Japanese version, the English translation of the game shorten his name as Luka and anime would address him/her as Ruka.
 * Luka's ending is the only outcome of the game in that Mayuri's death is definite, as Rintarou gave up on his attempts and decides to make Mayuri happy one last time instead. Mayuri also dies of natural causes (heart attack) in this ending.
 * Lab Member 006. Joined at episode 8. She is recruited by Okabe because she want to make a D-Mail to become a girl.