Everything is in the POV of the MC and FMC, it's your typical SoL/Romance with some character exposition, so learn more about the two of them but that's about it. It ends with FMC understanding that she's in love with MC

We have three main protagonists kind of, the MC and the FMC as well as a character referred to as 'Kurumi' or 'Kinomiya Madoka' (Kurumi was introduced in Vol1 already but her POV is shown in Vol2. She's in love with the MC and lives in the same apartment as FMC's sister, who we only knew from FMCs POV in Vol2. The interesting part is the timeline, because events that seemed mysterious in Vol1 get explained in Vol2 from Madoka's POV. I.e., in Vol1, FMC suddenly heard noise in their home, checked it out and her eyes ended up peering someone else's eyes, a young woman, that woman screamed and ran away. The MC shrugged this off, since they lived in a haunted building anyway and these things happen there apparently, but it turns out that this young woman was Madoka, we see the same event playing out in her POV.

Similar to Vol2, we again have three protagonists, this time the third one is Momiji, the FMC's sister. We see her POV, her struggles and characterization. The timeline is again a bit confusing because basically it happens at the same time as Madoka's POV; so the ending of Vol2 is continued in the ending of Vol3 and we end up with another cliffhanger...

(To explain) :

Vol2 ends with Madoka finding a picture drawn by Momiji that showed MC and FMC together, resolving the mystery of where the missing FMC went and ruining Madoka's love story.

Vol3 ends a bit after, from Momiji's POV. Momiji drew MC and FMC together and then Madoka told her to get ready, saying they'd go and visit them now, Madoka knows where MC lives after all.

We have no idea what happens after that since Vol4 has not come out yet. Vol3 was released in 2022...