A Certain Scientific Railgun: Astral Buddy is a manga spinoff of A Certain Scientific Railgun, focusing on Junko Hokaze – a member of Misaki Shokuhou’s clique.
The manga is an original story written by Kazuma Kamachi, with art by Yasuhito Nogi. It was originally published in Monthly Comic Dengeki Daioh. Seven Seas Entertainment licensed the manga for an English release.
This first volume contains chapters on through to five.

Front cover of the first volume of A Certain Scientific Railgun: Astral Buddy, featuring Kuroko Shirai, Junko Hokaze, the ghost that is haunting Junko, and Misaki Shokuhou
HIGH-SPIRITED FUN!
Hokaze Junko, one of the top “handmaidens” of Shokuhou Misaki, has always blended into the background of Tokiwadai – an easy feat when you go to an all-girls’ school full of powerful psychics. But when a ghostly figure starts stalking her, Junko is suddenly the centre of attention! As Junko investigates her stalker, she starts to learn new things about her classmates… and herself!
The events in this manga take place during A Certain Scientific Railgun‘s Dream Ranker Arc. Astral Buddy more or less foregoes any introductions for the majority of its cast, basically just assuming that anyone who picks it up has read the A Certain Scientific Railgun manga as well.
As such, there is something of a barrier of entry for this spinoff. With that said, I shall be offering my thoughts on this spinoff as someone who has read the main A Certain Scientific Railgun manga – including the Dream Ranker Arc.
The manga kicks off in pretty typical Railgun fashion – with Kuroko doing her duty as a member of Judgment. Kind of nice to see after there were large parts of Railgun where she had to sit out due to being injured.
But it is not Kuroko who is our main character here, but Junko Hokaze. Despite having a brief appearance in the Railgun manga, she went unnamed there. Now, she gets to be the star of her own spinoff.
The plot revolves around her being haunted by a ghostly figure – whether it is an actual ghost or some kind of esper ability remains to be seen, but a lot of this first volume is Junko investigating the identity of the amnesiac ghost girl.
That’s not all that Junko is dealing with. When the synopsis mentions discovering more about herself, it is almost certainly referring to Junko discovering her sexuality. The first chapter reveals she is dense when it comes to matters of love, but Kuroko is able to make her realise.
Junko is always very popular with other girls; Tokiwadai students, certain familiar faces and even at least one female teacher all express some form of attraction towards Junko.
Besides Kuroko, there are other familiar faces that show up in this volume too. Whilst the Railgun herself, Mikoto Misaka, is only mentioned in passing, two other girls from the Railgun manga get to play a more active role in this volume: Uihara Kazari and Saten Ruiko.
A Certain Scientific Railgun: Astral Buddy is a fun read, though one that comes with a caveat. If you haven’t read Railgun‘s Dream Ranker Arc, then you are probably not exactly going to really understand what is happening in Astral Buddy. I guess you could still get some enjoyment out of it, but it is better if you have a full understanding of the story surrounding Junko’s investigation.