"Imouto sae Ireba Ii" (all good as long as we have younger sister) volume 4 by Hirasaka Yomi. This volume features lively debates around the merits of having underwear versus being completely naked.
Actually there is a lot more than battle of underwear and counterattack of the naked, but those bits tend to leave a lasting impression after having devoted two chapters to this subject. This might sound like one of those pointless arguments that nobody should care about, but the characters are all absolutely serious about what's at stake, and the amount of passion that went into this seemly trivial subject made it a real joy to read. Highlights here include a detailed description of another detailed sketch of how a bath scene might unfold, when a scene from a novel is translated into manga, elaborated frame by frame. It inspired a great visualization with only words.
Just before the underwear bits was an introduction of a new character, whose favorite sister character was Sagiri from "Eromanga Sensei" series. That totally caught me off guard and I had a good laugh. Clearly there is a nontrivial overlap in readership for these two series, and this author is very aware of this overlap. Or perhaps it's actually a ploy to make "Imouto sae Ireba Ii" seem more realistic by referencing the other works of fiction. I enjoy seeing references like this, it's part of the reason why I look for novels about novels.
The rest of this volume was equally great, and generally more upbeat than volume 3. There is an extra chapter at the end that describes "Life of a Light Novel Writer", an uncannily realistic board game. Also available in audio form if you bought the special edition of volume 4. Of course I bought the special edition, not for the drama CD but for the picture of Chihiro in a wedding dress on the cover. This is a slow development where Chihiro gets slightly closer to revealing her true identity to her brother in every volume. Anticipation of that event is enough to keep me interested in this series. It hasn't happened in this volume, but maybe it's not too far away.
Looking forward to more sister madness in the next volume.
Previous (2016-04-05): "No Game No Life" volume 8 by Kamiya Yuu
Next (2016-04-21): "Eromanga Sensei" volume 6 by Fushimi Tsukasa