"Eromanga Sensei" volume 1 by Fushimi Tsukasa, illustrated by Kanzaki Hiro. A story about an illustrator, told from the perspective of a light novel writer. It's a great story on a developing brother-sister relationship, plus a few anecdotes on how novel writers work.
"Eromanga Sensei" is the pen name of Izumi Sagiri, the younger step-sister of Masamune and an accomplished illustrator. The name is apparently derived from Erromango island (as opposed to Eromanga in Australia, or the more obvious ero-manga), but of course no one in this book believed it. The three most memorable bits for me are Sagiri's reaction when she is being addressed as "Eromanga Sensei", all scenes depicting her state of bliss when she is drawing, and her reconciliation with her brother in the final chapter.
All events before the final chapter are mostly in developing the characters, which is quite an interesting feat considering that there is literally a closed door between Sagiri and her brother Masamune throughout most of the book. As the story progresses, readers see Sagiri and the door opening up slowly. Everything builds up to the climax where the siblings clear up their misunderstandings, after Masamune enters Sagiri's room with a very embarrassing novel in hand. Then the book ends with a cliffhanger.
Fushimi-sensei is probably best known for his work on Oreimo, another novel series on brother-sister relationship, with the same illustrator. Fans of the previous series can be assured that this one maintains the great character balance from the previous series, particularly in how the siblings get along. Besides the general character balance though, this is an entirely new series with a new set of characters. Personally I find this one to be much more digestible than Oreimo, partially due to the shorter title.
Lots of things to like in this first volume, looking forward to reading the next one.
Previous (2015-10-03): "No Game No Life" volume 7 by Kamiya Yuu
Next (2015-11-05): "Imouto sae Ireba Ii" volume 1 by Hirasaka Yomi