<p>Adding onto <a href="https://anime.stackexchange.com/a/3055">кяαzєя's answer</a>, a good resource that specifies the chronology of Index and Railgun in much more detail is the <a href="https://www.baka-tsuki.org/project/index.php?title=Index_Calendar" rel="nofollow noreferrer">Baka-Tsuki Unified Index Calendar</a>, which is an fan-compiled calendar of all events in the Toaru Majutsu no Index franchise.</p>

<p>As of January 2018, the calendar includes the following source materials, up to the specified issue (with the latest in-universe date specified in parentheses):</p>

<ul>
<li>(Light Novel) <strong>A Certain Magical Index</strong>: NT volume 19 (<em>Dec. 12</em>)</li>
<li>(Manga) <strong>A Certain Magical Index</strong>: chapter 123 (<em>~Oct. 7</em>)</li>
<li>(Manga) <strong>A Certain Scientific Railgun</strong>: chapter 100 (<em>~Oct. 14</em>)</li>
<li>(Manga) <strong>A Certain Scientific Accelerator</strong>: chapter 42 (<em>~Sep. 10</em>)</li>
<li>(Manga) <strong>Astral Buddy</strong>: chapter 7 (<em>~Sep. 28</em>)</li>
<li>(Anime) <strong>A Certain Magical Index</strong>: II episode 24 (<em>Oct. 3</em>)</li>
<li>(Anime) <strong>A Certain Scientific Railgun</strong>: S episode 24 (<em>Sep. 2</em>)</li>
</ul>

<p><a href="https://www.baka-tsuki.org/project/images/7/7d/A_Certain_Unified_Calendar.png" rel="nofollow noreferrer"><img src="https://www.baka-tsuki.org/project/images/7/7d/A_Certain_Unified_Calendar.png" alt="A Certain Unified Calendar.png"></a></p>

<p>The calendar is frequently updated.</p>

CC BY-SA 4.0
2018-06-23T19:22:05.367Z
2018-09-07T23:58:05.873Z
2018-09-07T23:58:05.873Z
ahiijny
<p>Railgun is a non-canon spinoff using the characters and setting of Index.</p>

<p>by that definition:</p>

<ol>
<li><p>I guess they take place in alternate universes.</p></li>
<li><p>They are indepedent besides setting and characters.</p></li>
<li><p>Watching both seasons of Index before Railgun is in my opinion for the better.</p></li>
</ol>

CC BY-SA 3.0
2013-02-26T23:32:04.340Z
Just want to expand on their independence - You can watch only Index and it will make sense. You can also watch only Railgun and it will also make sense. I don't think any parts of their stories rely on the other's stories. Personally, I don't really enjoy Index, but I think Railgun is great. I know people who think the opposite. If you don't like one, you don't need to watch the other for fear of not understanding something in the one you like.
atlantiza
CC BY-SA 3.0
2013-02-27T00:51:29.843Z
Thing about Index is that the parts of the novels that people really praise (God´s Right Seat, English Civil War and World War 3 arcs aswell as New Testament) havent been animated yet.
Christian Aurig Frøkjær
CC BY-SA 3.0
2013-02-27T14:48:02.277Z
Everything from the characters to plot in the Railgun series is canon to the main Index series, as the story was made by the author of the novels. This includes the Saten cameos appearance in the novels and "[Capacity Down](http://toarumajutsunoindex.wikia.com/wiki/Capacity_Down)" used on Accelerator in Volume 19 of the novels. This also works the other way with Railgun series. Everything that happens in the Railgun happen in the Railgun, hence why Eri and Harumi-sensei's students being cured are canon.
кяαzєя
CC BY-SA 3.0
2013-02-27T16:40:15.883Z
Being written by the same person doesn´t make it canon. Fate/Apocrypha is partially being written by Kinoku Nasu but it´s still not canon and instead an alternate universe. Even if they use props like the Capacity Down that were featured in Railgun, that doesn´t make Railgun canon.
Christian Aurig Frøkjær
CC BY-SA 3.0
2013-03-27T01:52:18.757Z
@ChristianAurigFrøkjær In *Fate/complete material IV*, Nasu mentions that *Fate/Apocrypha* is extra-canon. *Kara no Kyoukai* and *Tsukihime* are explicitly mentioned by the Nasu to be parallel worlds. In *Fate/complete material III*, it's confirmed that *Tsukihime* shares the same universe as *Fate*, stating that the end of *Tsukihime* happens at the beginning of *Fate/stay night.* While they are separate, all series in the Nasu-verse are considered canon to one another, one could presumptively travel to each, if they could use [Second Magic](http://typemoon.wikia.com/wiki/Second_Magic)...
кяαzєя
CC BY-SA 3.0
2013-02-26T23:25:24.173Z
2013-02-26T23:25:24.173Z
Christian Aurig Frøkjær
<p>Chronologically, <em>Railgun</em> comes first. Then near the middle of <em>Railgun</em> (the Level Upper Arc), the events and timeline start to converge with <em>Index</em>.</p>

<p>For an example, in episode 17 of the <em>Railgun</em> anime, Komoe-sensei mentions how she likes all her students, even the ones that blow up her roof, which is probably a reference to when Index used Dragon's Breath (episode 6 of <em>Index</em>). </p>

<p>The manga gives a better frame of reference, since it gives a exact date (July 16th). 
So the events in <em>Railgun</em> begin 4 days before the Index novel (July 20th), where Touma first meets Index. Touma <a href="http://www.baka-tsuki.org/project/index.php?title=Toaru_Majutsu_no_Index%3aVolume1_Prologue">meets</a> Mikoto on the eve of July 19th. </p>

<p>According to the <a href="http://tvtropes.org/pmwiki/pmwiki.php/Manga/ACertainScientificRailgun?from=Manga.ToAruKagakuNoRailgun">TV Tropes</a>:</p>

<blockquote>
  <p>The anime, however, violates this by adapting events from Volume 8 of the novels into the anime's first episode. As it stands, Chapters 18 to 39 occur around the time of Volume 3 in the novels, Chapter 40 is around volume 5, Chapters 41-42 and around volume 8 and Chapters 43-current take place around volume 9.</p>
</blockquote>

CC BY-SA 3.0
2013-03-26T23:00:35.640Z
2013-03-26T23:06:38.137Z
2013-03-26T23:06:38.137Z
кяαzєя
<p>According to MAL, the <a href="http://myanimelist.net/anime/4654/Toaru_Majutsu_no_Index">former</a> is the parent story of the <a href="http://myanimelist.net/anime/6213/Toaru_Kagaku_no_Railgun">latter</a>, that appears described as a side story. However, I find no reference to these questions:</p>

<p><strong>Do both stories take place in the same universe?<br>
Are they somewhat dependent on each other?<br>
If so, in which order should the series be watched?</strong></p>

CC BY-SA 3.0
2013-02-26T22:47:30.293Z
There's definitely some major inconsistencies in the Anime. The scene where Touma first meets Misaka is completely different between the two.
Mysticial
CC BY-SA 3.0
2013-02-27T14:54:34.703Z
While there are slight differences (as expected with different adaptations), there's nothing drastic that affects the continuity. E.g., in the novel Touma "slaps" away Mikoto's railgun, but in the manga he "catches" it. In the novel, the first hit that Touma lands on the Accelerator is a slap to his hand, but the Railgun manga he hits him square in the face.
кяαzєя
<a-certain-scientific-railgun><a-certain-magical-index>
How are "A Certain Magical Index" and "A Certain Scientific Railgun" connected?
# How are "A Certain Magical Index" and "A Certain Scientific Railgun" connected?
Posted by: username_0 on 2013-02-26
According to MAL, the [former](http://myanimelist.net/anime/4654/Toaru_Majutsu_no_Index) is the parent story of the [latter](http://myanimelist.net/anime/6213/Toaru_Kagaku_no_Railgun), that appears described as a side story. However, I find no reference to these questions:

**Do both stories take place in the same universe?  
Are they somewhat dependent on each other?  
If so, in which order should the series be watched?**
**Tags:** a-certain-scientific-railgun a-certain-magical-index
> **Comments:**
> **username_1**: There's definitely some major inconsistencies in the Anime. The scene where Touma first meets Misaka is completely different between the two.  
> **username_2**: While there are slight differences (as expected with different adaptations), there's nothing drastic that affects the continuity. E.g., in the novel Touma "slaps" away Mikoto's railgun, but in the manga he "catches" it. In the novel, the first hit that Touma lands on the Accelerator is a slap to his hand, but the Railgun manga he hits him square in the face.  
---
## 3 answers
### Answer by username_2 on 2013-03-26. Score: 19 | Accepted answer
Chronologically, *Railgun* comes first. Then near the middle of *Railgun* (the Level Upper Arc), the events and timeline start to converge with *Index*.

For an example, in episode 17 of the *Railgun* anime, Komoe-sensei mentions how she likes all her students, even the ones that blow up her roof, which is probably a reference to when Index used Dragon's Breath (episode 6 of *Index*).

The manga gives a better frame of reference, since it gives a exact date (July 16th).
So the events in *Railgun* begin 4 days before the Index novel (July 20th), where Touma first meets Index. Touma [meets](http://www.baka-tsuki.org/project/index.php?title=Toaru_Majutsu_no_Index%3aVolume1_Prologue) Mikoto on the eve of July 19th.

According to the [TV Tropes](http://tvtropes.org/pmwiki/pmwiki.php/Manga/ACertainScientificRailgun?from=Manga.ToAruKagakuNoRailgun):

> The anime, however, violates this by adapting events from Volume 8 of the novels into the anime's first episode. As it stands, Chapters 18 to 39 occur around the time of Volume 3 in the novels, Chapter 40 is around volume 5, Chapters 41-42 and around volume 8 and Chapters 43-current take place around volume 9.
---
### Answer by username_3 on 2018-06-23. Score: 1
Adding onto [кяαzєя's answer](https://anime.stackexchange.com/a/3055), a good resource that specifies the chronology of Index and Railgun in much more detail is the [Baka-Tsuki Unified Index Calendar](https://www.baka-tsuki.org/project/index.php?title=Index_Calendar), which is an fan-compiled calendar of all events in the Toaru Majutsu no Index franchise.

As of January 2018, the calendar includes the following source materials, up to the specified issue (with the latest in-universe date specified in parentheses):

* (Light Novel) **A Certain Magical Index**: NT volume 19 (*Dec. 12*)
* (Manga) **A Certain Magical Index**: chapter 123 (*~Oct. 7*)
* (Manga) **A Certain Scientific Railgun**: chapter 100 (*~Oct. 14*)
* (Manga) **A Certain Scientific Accelerator**: chapter 42 (*~Sep. 10*)
* (Manga) **Astral Buddy**: chapter 7 (*~Sep. 28*)
* (Anime) **A Certain Magical Index**: II episode 24 (*Oct. 3*)
* (Anime) **A Certain Scientific Railgun**: S episode 24 (*Sep. 2*)

[![A Certain Unified Calendar.png](https://www.baka-tsuki.org/project/images/7/7d/A_Certain_Unified_Calendar.png)](https://www.baka-tsuki.org/project/images/7/7d/A_Certain_Unified_Calendar.png)

The calendar is frequently updated.
---
### Answer by username_4 on 2013-02-26. Score: -2
Railgun is a non-canon spinoff using the characters and setting of Index.

by that definition:

1. I guess they take place in alternate universes.
2. They are indepedent besides setting and characters.
3. Watching both seasons of Index before Railgun is in my opinion for the better.
> **Comments:**
> **username_5** (2013-02-26): Just want to expand on their independence - You can watch only Index and it will make sense. You can also watch only Railgun and it will also make sense. I don't think any parts of their stories rely on the other's stories. Personally, I don't really enjoy Index, but I think Railgun is great. I know people who think the opposite. If you don't like one, you don't need to watch the other for fear of not understanding something in the one you like.  
> **username_4** (2013-02-27): Thing about Index is that the parts of the novels that people really praise (God´s Right Seat, English Civil War and World War 3 arcs aswell as New Testament) havent been animated yet.  
> **username_2** (2013-02-27): Everything from the characters to plot in the Railgun series is canon to the main Index series, as the story was made by the author of the novels. This includes the Saten cameos appearance in the novels and "[Capacity Down](http://toarumajutsunoindex.wikia.com/wiki/Capacity_Down)" used on Accelerator in Volume 19 of the novels. This also works the other way with Railgun series. Everything that happens in the Railgun happen in the Railgun, hence why Eri and Harumi-sensei's students being cured are canon.  
> **username_4** (2013-02-27): Being written by the same person doesn´t make it canon. Fate/Apocrypha is partially being written by Kinoku Nasu but it´s still not canon and instead an alternate universe. Even if they use props like the Capacity Down that were featured in Railgun, that doesn´t make Railgun canon.  
> **username_2** (2013-03-27): @ChristianAurigFrøkjær In *Fate/complete material IV*, Nasu mentions that *Fate/Apocrypha* is extra-canon. *Kara no Kyoukai* and *Tsukihime* are explicitly mentioned by the Nasu to be parallel worlds. In *Fate/complete material III*, it's confirmed that *Tsukihime* shares the same universe as *Fate*, stating that the end of *Tsukihime* happens at the beginning of *Fate/stay night.* While they are separate, all series in the Nasu-verse are considered canon to one another, one could presumptively travel to each, if they could use [Second Magic](http://typemoon.wikia.com/wiki/Second_Magic)...  
---
