Toaru Kagaku no Railgun Manga Volume 04

Toaru Kagaku no Railgun Manga Volume 04 is the fourth volume released for the Toaru Kagaku no Railgun Manga.

The tankobon details the first half of Misaka Mikoto's side of the Sisters Arc, as she discovers that there are clones of her, much to her horror. She later bonds with one, but soon discovers that true nature of the clones' purpose, as she witnesses the horrific death of her clone at the hands of the Accelerator.

Publisher's Summary
Breaking into a new episode! Mikoto has clones called Sisters!?

"Clones of the Railgun live in the city." Mikoto has heard of such urban legends. However, she begins examining the truth behind it despite believing it all to be a hoax. Then one day Mikoto meets one of these Sister clones, and discovers the cruel truth hidden from her...!

Chapters

 * Chapter 018: August 10, Part 1
 * Chapter 019: August 10, Part 2
 * Chapter 020: August 11
 * Chapter 021: August 15, Part 1
 * Chapter 022: August 15, Part 2
 * Chapter 023: August 15, Part 3