"Revelation" (啓示 Keiji?) is the 79th chapter of the Toaru Kagaku no Railgun manga series, released on August 27, 2015.
Still using the Indian Poker cards to find the Bust Upper, Misaka Mikoto jumps into Yoshikawa Kikyou's dream where she measures her bust and compares it to her friend, Yomikawa Aiho. She later sees her waist measurement and finds that it has increased, much to her horror. Mikoto wakes up and says that she shouldn't assume that she would "grow" eventually lest she'll turn out like Kikyou.
Meanwhile, Saiai is in the dream of Tsuchimikado Maika, wearing a maid outfit. Tsuchimikado Motoharu appears with the Loli Ocean Demon King Bra Maid outfit, which makes Saiai assume that he is a pervert. Motoharu flatters her, and Saiai notices that the Maika isn't all that opposed as she lets on, but still eventually rejects him.
Mikoto meanwhile jumps into a roadside artist's dream and finds Fusou Ayame there, where she later tells Mikoto that she wears her outfit because she wanted to show her audience that she is the real deal, in that she doesn't use pads. Mikoto however, points out that she could've used an outfit that hides her body lines. In Saiai's dream of being Kuruwa, she reads the Iga Clan's seduction techniques, much to her frustration as it puts emphasis on breasts. Saiai is however impressed that if one doesn't have ample breasts then they could use their legs, though she gets angry after it states that breasts are still the best. An employee later arrives into their room after Saiai's screams of anger annoys the other customers. Mikoto is in Himegami Aisa's place, decrying her fate in the background while Fukiyose Seiri shines even in a classroom full of colorful characters. Aisa points out Seiri's large breast compared to her meager C-Cup. This ridiculous complaint however, angers Mikoto, and she wakes up screaming.
After being forced to leave from the cafe, Mikoto and Saiai make use of an open lounge in a hotel and continue using the Indian Poker cards. As the dream, a crow notices a shiny card on top of their deck and takes it away. Little do they know that that would be the one thing they were searching for all along: the Bust Upper.
Mikoto enters a "dream" which is not like the others as she isn't living out the dream as anyone. Suddenly, a girl with streaks on her hair starts speaking cryptically to her about the future. In the end, she speaks to Mikoto of a threat that she cannot ignore, and that if she eliminates it would only lead to another one. The dream ends with the girl asking her what she would do.
As the day winds to an end, the crow that stole the card lands on a tree, where it is scared off by Sphynx the cat, losing its grip on the card. It then falls next to a girl who has bought Indian Poker cards and assumes that is one of her purchases. With the girls using up all the cards, they become frustrated that the card merchant lied to them as the card isn't in the deck they bought. They then both go home. In ITEM's hideout, Saiai meets with Shiage. He apologizes for buying her milk because he assumes that it would help her grow taller, referencing the time she tried to use him to fake her age. Hearing this, Saiai just kicks Shiage for being misleading. Back with Mikoto, she relates the day with Kuroko as the night grows late.
The next day, Ruiko is walking with Kazari talking about her plans about with the Indian Poker cards, at which point they pass by the lady who got the card by accident. The Breast Upper is real as Ruiko notes how large her breasts are.
- Misaka Mikoto and Kinuhata Saiai continue to go through the Indian Poker cards to find the Bust Upper. In one of the dreams, Mikoto encounters a mysterious girl in a labcoat.
- While they are sleeping, one of the cards is stolen by a crow, ending up in the possession of a girl who later appears with a greatly increased bust.
- Yomikawa Aiho
- Himegami Aisa
- Tsuchimikado Maika
- Misaka Mikoto
- Kinuhata Saiai
- Aogami Pierce
- Kamijou Touma...?
- Fukiyose Seiri
- Hamazura Shiage
- Shirai Kuroko
- Saten Ruiko
- Uiharu Kazari
- Yoshikawa Kikyou
- Fusou Ayame
- Tsuchimikado Motoharu
- Spiky-haired glasses girl
- Kuriba Ryouko (unnamed)
No known magic or esper powers were used or referenced this chapter.
- Motoharu's apartment (fantasy)
- A Certain High School
- Seiri posing with Aisa hiding behind her is taken from one of Haimura Kiyotaka's sketches of the character.
- Kuriba_Ryouko appears in Mikoto's dream; she is not named until Railgun Manga Chapter 85.
- Dream Kikyou referencing her new "NEET" lifestyle is a reference to the fact that she had no employment after the events of August 31 with Accelerator in the timeline.
- Shiage references the events that Saiai mentioned last episode where he bought her milk assuming that it would her grow.
- Shiage relates how he had help her fake her age by forging an ID in order to watch an R18 movie, an event that is directly taken from Toaru Majutsu no Index Light Novel Volume SS2.
- The girl that acquired the Bust Upper is the same girl that was buying cards from the Indian Poker merchant prior to Misaka Mikoto meeting Kinuhata Saiai in chapter 77
- Who is that mysterious girl with the lab coat in Mikoto's dream?
- Saiai: "Super shut up!!! I can just get a guy's obedience with my fists!! If you idiots love those lumps of fat so much, eat nothing but fatty foods, writhe in pain from gout, and die!!!"--regarding Kuruwa's dream.
- Mikoto: "That's plenty!!! You're overshadowed with a C cup? What are you supposed to do with less than that? Dig a hole in the ground? Try thinking how it feels for those of us who barely have anything there..."--regarding Aisa's dream where she complains about her C-Cup.