"Imouto sae Ireba Ii" (all good as long as we have younger sister) volume 12 by Hirasaka Yomi. Everyone took a circuitous route to resolve their conflicts in this volume.
The drastic change in characters is visible right on the cover: Itsuki decided to become a monk after almost having sex with a minor, and was suspected of becoming gay a short while after that. Nayuta has her hair cut short after abandoning her career as a writer and taking up hardcore gaming instead. The last volume ended on a low point and this volume is where the fall out is observed.
Yet, somehow it all came together in the end, with the power of younger sisters, in an ending fitting for novel writers. The particular plot here wasn't new considering that Eromanga Sensei did it way back in volume 1, but the way it's done here show a level of planning, humor, and madness that are trademarks of this series.
It felt like the series could have ended there, but actually there are still two more volumes to go (as announced in the afterwords for this volume). Looking forward to a good ending for Chihiro.
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Next (2019-06-24): ICFP 2019 postmortem