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Arc Almanac

21 Oct 2026Draft. Not yet checked against the books.

All series / A Certain Magical Index / Arc 10

Arc 10 of 66 in A Certain Magical Index

Arc 10: Big Spider

In the story: Aug

Arc name chosen by Arc Almanac, because the books don’t name it.

I’ve watched through

Earlier in story order than the end of Index I.

Seen by the end of Railgun.

Earlier in story order than the end of Index II.

Earlier in story order than the end of The Miracle of Endymion.

Seen by the end of Railgun S.

Earlier in story order than the end of Index III.

Earlier in story order than the end of Accelerator.

Seen by the end of Railgun T.

Item (episodes 1–2; airing) stops before this arc.

What happens

Attacks on espers lead Judgment to a Skill-Out gang called Big Spider. Konori's connection to the group complicates an investigation that reaches beyond a simple confrontation between people with powers and people without them.

Where it sits

Big Spider in A Certain Magical Index
FormatVolumesUnitsLanguage
Manga — A Certain Scientific Railgun—CutJapanese
Manga — A Certain Scientific Railgun—CutEnglish
Anime — A Certain Scientific RailgunRailgunSeason 1, episodes 15–16—

Draft. Not yet checked against the books. Report a wrong mapping.