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 series.

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 18: August 10, Part 1
 * Chapter 19: August 10, Part 2
 * Chapter 20: August 11
 * Chapter 21: August 15, Part 1
 * Chapter 22: August 15, Part 2
 * Chapter 23: August 15, Part 3