The most prevalent and recognized side media in the series and somehow has never received a localization. Oh well. The plot is simple: An alternate personality, Otonoashi Ryoko is an amnesiac student somehow in HPA and the story essentially tells bits and pieces of how she orients herself throughout the school with her notebook, her meetings with her boyfriend Matsuda Yasuke, his attempts to "cure" her condition with that plan having ulterior motives as well as brief moments with the schools operations such as the Steering Committee and how they do things.
As light novels go, I'd say this is generic in terms of quality and structure. Yes we get a bit of plot and how it ties into the games and events overall but I'll focus on the overall writing style. Is it good? Slightly. It's alright at most parts, but the obnoxious exaggeration of sound effects and dialog really gets to me most times and not only that it's constantly repeated, leading to some irritation and some reduction in IQ. Notable examples:
- "Matsuda Matsuda Matsuda Matsuda Matsuda Matsuda Matsuda Matsuda."
- "Siiiiigh...... Zzzzzzzzzz... Zzzzzzzzzzzzzzzzz......GYAAAAAAAAH!"
- "―M...Matsuda! C‘mon, Matsudaaaa!!"
- "I turned my eyes down to my notebook following Enoshima-san‘s urges, and then – SMASH! FWOOOOSH! CRACK! WHOOP! SWISH! TATATATATA!"
...You get the point. Essentially the MC's repitition of "Matsuda" on the scale far too often grated my eyes, and as such the sentence should have easily been written differently. The characters, some having less papertime than others are written in a simplistic and straightforward way, with little additional info being presented and as such, take up mostly by dialog. Everything else about the light novel is simplistic and lackluster, with dialog being the dominant factor of character interactions and events and scenes written simplistically with little descriptions as well as the overuse of sound effects literally being written out.
As for fanmade "localization" attempts, many people have shot their attempt at translation and the results are mostly the same, if not similar. You can translate and interpret as many times as you want and the result wouldn't change. The main structure of the story is inheritally shoddy and of lower quality in terms of detail and structure, which essentially is basic enough for anyone to read and any claims of "mistranslation" and the like are full of crap anyway.
Overall it's an ok read, and the story does expand on DR's storyline as well as the introductions of some new/LN exclusive characters. In terms of structure and quality it needs work but it's a light novel so they're all the same anyways.