A Certain Magical Index series is one of the series I love that doesn't get much mainstream recognition. It's one of my first Light Novels and it's the one I stuck with the longest. If you're new to the series the basic premise is:

Academy City is a scientific advanced city that managed to create super powers based on Science. Except that in this world Magic also exists and it stays hidden from normal people. Science & Magic sides are always at war with each other.

• The main story called Magical Index: follows Kamijou Touma as he gets involved in the war between Science and Magic after saving a girl called Index who has all Magic books stored in her head.

• The spin-off story called Railgun: follows Misaka Mikoto the third ranked Esper is Academy City as she tries to protect her daily life from the Dark Side of the city of super-powered children & crazy scientists.

The two stories happen around the same time with the main story events affecting Railgun, while the spin-off provides more lore that gets incorporated in the main story. You can watch one without the other but you'll miss many things if you do.

All of Raildex/Toaru universe arcs through various works (anime/manga/novels) share the same timeline and unless stated otherwise, any event in series is canon to all of them.

Since there are many of works that share the same universe it's hard to decide where to start. While most of Index/Railgun stories are self-contained, characters and plot-points can be introduced in one series then appear without introduction in the other.

So, which order should I watch the series?

The short version:

• Index I -> Railgun -> Railgun S -> Index II -> Index III > Accelerator -> Railgun T

I would advice people who have time to watch the anime series in the order they were released. (The order above is similar to, but not exactly the release order.) The animation gets better with every new season (Railgun T is better animated than Index III which is (arguably) better than Railgun S and so on.)

Railgun First Version:

• Railgun -> Railgun S -> Index I -> Index II -> Index III > Accelerator -> Railgun T

Watching this way you might feel more connection to Mikoto because since if you start the story is from her perspective you won't understand what she doesn't understand about the world. (Which is a lot that's explained in Index!)

The hero of the original: Kamijou Touma will seem so much more mysterious if you started with Railgun as Mikoto doesn't know anything about his other adventures.

Note: In my opinion the first arc of Index is essential though.

It contains most of the needed world building and establishes Kamijou Touma's character. Watching Railgun first (especially when you reach Railgun S,) Touma's interactions might feel random as Railgun is strictly a Science-side story while most of Touma's conflicts are with the magic side.

The Chronological Order Version:

Another way to watch the series is by watching in Chronological Order. Watching chronologically isn't always better.

The writer assume that you have watched/read everything that was released up to that point while using a character/plot-point earlier in the timeline. He uses the prior-knowledge of the fans to spice the story up!

For example: Sisters Arc in Railgun is written assuming the audience have watched the same arc in Index first. It glosses over Kamijou's part of the story while giving a huge development to Misaka before & after the main events of the arc. (Many of the scenes used the audience knowledge against them to spur emotions.)

Here's the Chronological Order of the major events, I won't mention some arcs because they're not too relevant to my list. Don't skip them though. Every arc progresses its respective series plot in a way.

• Level Upper Arc (Railgun ep01-14.)

• Index Arc. (Index ep01-06) [Happens at the same time as the latter Level Upper Arc events.]

• Sisters Arc (Railgun.) (Railgun S ep01-16. Same arc as below: Misaka's perspective.)

• Sisters Arc (Index.) (Index ep10-14. Same arc as above: Kamijou's perspective.)

• Angel Fall Arc. (Index ep15-17)

• Three Stories Arc. (Index ep18-20 + Index II ep01.)

• Kazakiri Hyouka Arc. (Index 21-24.)

• Orsola Aquinas Rescue Arc. (Index II ep02-05.)

• Tree Diagram Remnant Arc. (Index II ep06-07.) [Explains Kuroko's Injuries in Railgun T.]

• Daihasei Festival Arc (Index) (Index II ep08-13)

• Daihasei Festival Arc (Railgun) (Railgun T 01-16) [Same time but no shared events with Index.]

• Dream Ranker Arc (Railgun T's Second Half.) [Spans several days. Multiple Index arcs.]

• Academy City Invasion Arc (Index II ep17-23) [This arc events results in the whole Index III.]

• Battle Royal Arc (Index III ep04-06) [Some Railgun characters were first introduced in the novel version of this arc in Index.]

I didn't include Accelerator's anime's Necromancer arc as I don't know where it fits in the timeline yet. Anyway, my recommendation for the chronological watching is as follows:

Index (01-06) -> Railgun (first season) -> Index (07-09) -> Railgun S (01-10) -> Index (10-14) -> Railgun S (11-24) -> Index (15-24) -> Index II (01-13) -> Railgun T (01-16) -> Index II (14-24) -> Index III (01-06) -> Railgun T (17-25) -> Index III (07-26)

That was longer than I thought it would be.

For now, what do you think?

This article is heavily edited from the original version first published on HIVE.