Episode 9
Chaos Theory Homeostasis II
Ep09 - feiris and akiba
Japanese Name: 幻相のホメオスタシス
Romaji Translation: Gensō no Homeosutashisu
Release Date: June 1, 2011
Production Staff
Screenplay: Jukki Hanada
Storyboard: Tomoki Kobayashi
Director: Tomoki Kobayashi
Theme Music
Opening Song: Hacking to the Gate
Ending Song: Toki Tsukasadoru Juuni no Meiyaku
Episode Navigation
Previous: Episode 08: Chaos Theory Homeostasis I
Next: Episode 10: Chaos Theory Homeostasis III
Episode Glossary
Chaos Theory Homeostasis II (幻相のホメオスタシス, Gensō no Homeosutashisu) is the ninth episode of the anime adaptation of the visual novel Steins;Gate .

Okabe grows concerned over the drastic changes his experimentation is causing, and the IBN 5100 disappears from the lab. The only hope for finding a replacement rests upon the delicate shoulders of Feiris the cat girl.


August 6, 2010, 1:07 PM.

Rintarou discusses their discovery of D-Mails with Daru inside May Queen Nyan-nyan, but Daru points out that they were unable to change Daru's luck in his match with Feiris, to which Rintarou responds by blaming Daru himself for his loss. Despite the issues found in the system, Rintarou claims that a time machine is just a few fixes away.

Unfortunately for Rintarou, Feiris caught wind of his blabber and asks more about it... all while staring deeply into his eyes. Rintarou seems immune to Feiris' charms, but Daru quickly gives in to her request.

Upon finding out what they are talking about, Feiris shows interest in "sending text messages into the past".

Rintarou soon returns to the Future Gadget Lab, still disappointed that Daru spilled the beans on their latest project. As he heads to the rooftop to dry some laundry, he sees Kurisu arguing with someone over the phone. Kurisu quickly heads back downstairs, and soon confronts Rintarou, pointing out that she is not crying, although it is clear that she is upset. Eventually, Kurisu sits beside Rintarou and breaks down on Mayuri's Oopa pillow.

Although Rintarou couldn't think of what to do for Kurisu at that moment, he tells her that he can listen to her sorrows anytime as someone important to him.

It turns out that it was all just a ruse.

Meanwhile, back at May Queen Nyan-nyan, Feiris decides to visit Mayuri after the end of her shift. Mayuri tells Feiris what she thinks about Okabe's Phone Microwave, and although she finds the idea of a time machine a bit exciting, she feels like Rintarou is leaving her when he is busy tinkering it.

Soon, Mayuri, dressed in her school uniform, visits the Future Gadget Lab to bring some lunch to Rintarou and his friends. Daru seems interested in Mayuri wearing a school uniform, and Kurisu is forced to warn Daru about his thoughts. Meanwhile, Rintarou is slowly becoming impatient as his supposed round-table meeting ends up being just a simple lunch. It seems that no one takes his agenda of physical time travel seriously... for a good reason.

Kurisu explains that no one, even SERN, was able to successfully send a human back in time, and their current device can only send 36 bytes of data plus a few bytes extra. However, the SERN's usage of lifters and black holes appear to be similar in principle to the Phone Microwave, although Kurisu notes that their device doesn't have a lifter in the first place.

Pessimistic about the Phone Microwave in its current status, Kurisu wants Okabe to handle its current issues for the meantime. Rintarou stubbornly refuses, finding that task boring, and the disappointed Kurisu eventually leaks her inner "neler" (i.e., @channeler) to Daru and Okabe.

Okabe soon decides to ask reports about their investigation, with Kurisu being ridiculed for her knowledge of Internet memes. Daru then reports that he is caught in a hitch and cannot proceed until he could start the analysis of the IBN 5100.

Rintarou is shocked at his report, and even more so when he finds no IBN 5100 at the Future Gadget Lab.

He soon explains this to Kurisu, who quickly assumed that the D-mail they last sent caused him to lose track of the IBN 5100. Rintarou is in disbelief, pointing out that their experiment only dwelled on minor events. Kurisu then explains that the Butterfly Effect was the explanation for such major changes, and one of the well-recognized risks in changing the past.

Rintarou then asks about the current whereabouts of the IBN 5100. Kurisu corrects the question: "Where was it?"

After a short phone call with Ruka, Rintarou confirms that there was an IBN 5100 in Yanabanashi Shrine, but is currently elsewhere. Kurisu discovers that they might be at a dead end, but Rintarou has an idea about who might know...

As Feiris prepares for a Q&A portion at the May Queen Nyan-nyan, she receives a call from Rintarou, asking her about an IBN 5100. Feiris confirms that her father has a lot of old PCs, but does not have an idea about an IBN 5100. Then, Feiris asks Okabe whether it has something to do with the time machine he has talked about before.

Rintarou soon goes on a visit to Feiris' place by her request, and Daru and Mayuri tag along, although Okabe preferred going alone. Soon, Rintarou hears someone say "IBN 5100" and catches a glimpse of Moeka Kiryuu from a distance. After a frantic chase by Okabe, he sees Moeka slumped on the ground, as if despairing after not being able to find something. Rintarou soon finds out that Moeka also had no idea where the IBN 5100 is.

As Moeka quietly walks away from him, Mayuri and Daru catch up to him. Rintarou is surprised to discover that both knew Moeka despite the fact that she disappeared from everyone else's memories when Moeka sent her D-mail, although Moeka did return when Ruka sent her D-mail.

Soon, they reach Feiris' address, and after a long way up, they head to Feiris' house at the topmost floor of Akihabara's tallest building.

Feiris soon welcomes them personally, and after Rintarou's demands, Feiris reveals to them that she is Rumiho Akiha, the daughter of the owner of Akihabara and the girl who brought the culture of moe to Akihabara.

However, it seems that Rintarou is not interested in moe, and quickly asks Feiris about the whereabouts of the IBN 5100. Feiris decides to tell them, but only if they will allow her to use the D-mail once, to which Okabe quickly objects to. Rintarou, after learning about the Butterfly Effect, becomes more cautious in letting more D-mails be sent, but Mayuri and Daru's pleas, along with the risk that may help bring back the IBN 5100, made Rintarou reconsider his decision, but only if Feiris agrees to become a Lab Member.

Soon enough, Feiris becomes Lab Member #007.

Feiris prepares her message and asks Rintarou to send to ten years into the past, and refuses to divulge its contents despite Rintarou's requests. After being pressured to leave the message to Feiris, Rintarou endures the next few minutes being hung up by Kurisu, who is supposed to handle the Phone Microwave.

Okabe is forced to act polite just for Kurisu to operate the Phone Microwave.

As the Phone Microwave becomes ready to use, Feiris shows some hesitation in sending the D-mail. However, with Okabe's cue, Feiris decides to press "send".


Soon after, a nauseous Rintarou finds himself alone with an unfamiliar man, which is later revealed to be none other than Feiris' father. Daru and Mayuri soon comment on Feiris' father's refined air, and Rintarou soon takes the chance to ask about the IBN 5100 he has been looking for. Unfrotunately for Okabe, Feiris' father has long parted with his IBN 5100 a long time ago, and clarifies that he did not send it to a shrine.

Rintarou still has the IBN 5100 in his head after leaving Feiris' home, and now, the chances that the Yanabanashi Shrine had gotten the IBN 5100 are now down to 0%.

However, that is not that only thing Rintarou is worried about.

He thinks that he may have changed something that he hasn't noticed... and it may be possible that he will never have the chance to change it back.

Soon, Mayuri thinks of going to Nakano to buy some doujinshi, and as Mayuri mentions wanting to have a Toranoana in Akihabara, the confused Okabe points out the Toranoana nearby—

Only to find that he is no longer in an Akihabara that is the city of otaku and moe culture.


By order of appearance

New CharactersEdit



Cultural ReferencesEdit

  • Kurisu's quote that leads to her being found out as a "neler" is "This guy's no good, if I don't do something fast..." (駄目だこいつ・・・、早く何とかしないと, Dame da koitsu... hayaku nantoka shinai to) is a real 2chan meme which originates from a quote in chapter 26 of the manga Death Note.
  • Okabe's line looking down from Faris' apartment, "The people are like garbage" (人がゴミのようだ, Hito ga gomi no you da) is a quote from the 1986 Studio Ghibli movie Castle in the Sky.


  • "I'll only say this. You're part of my life now. Anytime you want to talk, I'll listen." — Rintarou's "assuring message" to Kurisu
  • "99.9% of science is boring." — Kurisu's response to Rintarou's lack of interest to proceed with mundane tasks with the Phone Microwave