"July 18, Part 1" (七月十八日① Shichi-gatsu Jū-hachi-nichi ①?) is the fourth chapter of the Toaru Kagaku no Railgun manga series, published on May 21, 2007. This chapter is the first part of the Graviton bombings story.
Shirai Kuroko is explaining to Misaka Mikoto what happened to Konori Mii and an unknown Judgment officer last evening. They were evacuating everyone from a local store because they had detected graviton acceleration there. A doll exploded, and the unknown Judgment officer was badly injured when he protected an injured person. Mii, however, was able to protect herself and the shop owner with a shield. Kuroko also explains that the bomber has the ability to cause aluminium to explode by accelerating gravitons, and uses this on aluminium spoons hidden in dolls or aluminium cans in bins. Mikoto points out that it should be simple to find the culprit by searching for this type of ability in the Bank, but Kuroko says that there is only one person with that kind of ability and she has been in a coma for the last eight days. Kuroko wonders if it has something to do with the espers who are increasing their powers rapidly.
Meanwhile, Saten Ruiko calls Uiharu Kazari's name and flips her skirt (something she does constantly). Saten thinks Uiharu calls her name way too formally and suggests that they get closer with each other. Saten shows Uiharu her new music tracks that she got, while a strange boy with earphones walks by. The boy bumps into some other fellows, and they start to beat him up. A Judgment officer comes by and the boy complains that the officer should've come sooner.
In the classroom of Sakugawa Middle School, Uiharu and Saten are learning about AIM Diffusion Fields. Saten asks Uiharu if she wanted to go to the Seventh Mist and starts teasing her. The teacher overhears their conversation and smacks their heads with a piece of paper. When they both get out of school they meet up with Mikoto. Saten drags Uiharu off somewhere else asking how she knew a student from Tokiwadai. Uiharu answers by saying she knows her indirectly from Judgment and finishes off by saying that she is Misaka Mikoto, the Railgun. After Uiharu and Saten praise her, Mikoto asks if can go shopping with them, and they agree.
The same strange boy seems to have gotten in trouble again. Some delinquents start asking him for money. After he refuses he gets beat up again. The delinquents mention how they distracted Judgment by creating a mess in the hallway. The boy thinks to himself that Judgment is failing to do its job.
Saten starts asking if there is such a thing called a "Level Upper". She starts thinking if it was real and if she would use it. Uiharu reassures her by saying that those are just rumors people create on the web. Mikoto takes this into consideration, that this might be why they couldn't track down a suspect from the graviton cases.
Kuroko is exhausted in her Judgment office room looking for clues of the graviton case. She remembers that nine Judgment officers have been injured and considers it suspicious.
The strange boy decides that he's not going to wait for Judgment officers anymore, and that he's going to take matters in his own hands. He sees Uiharu, with a Judgment armband, going inside the Seventh Mist with her friends. With a sinister expression, he takes out an aluminium spoon from his bag.
- Electromaster (Railgun-variant) - Misaka Mikoto (officially introduced in cover)
- Synchrotron - Kushiro Katabira, Kaitabi Hatsuya
- The Judgment Boy and the Twin Tails Girl he saves reappear in Chapter 31, and Chapter 69. In Chapter 31, the officer and the girl are in casual wear and blushing, hinting that they're on a date. In Chapter 69, they're taking part in the bonfire dance together.
- Uiharu mentions that Mikoto railguned the bank robbers from Chapter 1.
- Saten's music player looks similar in design to an iPod Nano 2nd generation.
- What did Kaitabi Hatsuya mean when he was going to take matters in his own hands?
- Saten Ruiko: U~~i~~haru, Good Morning!! - to Uiharu flipping her skirt