"Seishun Butayarou wa Logical Witch no Yume wo Minai" (rascal does not dream of logical witch) by Kamoshida Hajime. This is volume 3 of the series, featuring the separation and reconciliation of the same personality.
The person who became two persons is Futaba Rio, and the mechanism which this separation was done was explained in the first chapter as quantum teleportation. This follows the same quantum physic theme like the first two volumes, but since quantum teleportation is a lot more subtle and easily misunderstood, the connection here didn't feel as strong as the first two volumes. Although there was one interesting detail on how both Rio never appears in the same scene, and each Rio is a reflection of whoever observes her. It's very subtle.
Nits aside, the story itself is strong as ever. The central theme is that despite the dissonance that resulted in two distinct instances of Rio, both versions of Rio are real, and neither is redundant. Whereas other stories might have gone the route of keeping only the good half of a person as a way of character growth, this volume made a point of keep all the bad parts. It was an interesting theme, and executed to perfection with snappy dialogues, consistent with the first two volumes.
This volume covers episodes 7-8 of the anime series. Despite having a few more pages than volume 1, this volume got compressed into fewer episodes with some of the key dialogues cut, and some of the key scenes disappeared altogether. Perhaps those scenes were reserved for future episodes? But at least they did keep the most important punchlines in the hospital scene.
Looking forward to the sister action in the next volume.
Previous (2019-06-28): "Seishun Butayarou wa Petit Devil Kouhai no Yume wo Minai" by Kamoshida Hajime
Next (2019-08-10): "Kino no Tabi 22" by Shigusawa Keiichi