It took 19 hours, but I've finally reached the first ending. I think? I had thought it was Minakami's route, but that particular Steam achievement didn't trigger, so I could be wrong. (Edit: It was definitely Minakami's route. For some reason, it took longer than it should have for the achievement to trigger.) At any rate, I'm glad I knew from reviews to restart the story and hit "skip" until a choice came up, because my first playthrough had zero choices to make and didn't end with any indication, other than "Chapter 1" in the ending credits, that there was more story to read.
This is a twisty historical SFF time travel story with murder, suicide, requited and unrequited love, and a not-entirely-reliable writer/bookstore employee narrator who has a tendency towards hallucinations. The main character, Tamamori, has three childhood friends, Minakami, Kawase, and Hanazawa, who all have secrets and are maybe not as close to Tamamori as he thinks. There's also another character, the Professor, who seems to have a crush on Tamamori for no particular reason other than that he likes Tamamori's writing.
The first ending involved some unexpectedly explicit sex that felt like someone had suddenly reminded the author that on-screen sex scenes were in their contract and they needed to find a way to fit them in somehow. The sex itself fit with the way the characters' relationships had developed - it was just the explicitness of it that felt out of place, after more than 18 hours of nothing more than "I love you" and eventually a few rare kisses or touches.
Parts of the story were absolutely grueling - I didn't expect one particular character to die as often as he did - but I enjoyed it as a whole. It took hours to really get going, but once it did, I resented chores and work that took me away from getting to read a bit more. I'm hoping the remaining routes are as enjoyable, and that I'll be able to get through them all before my flight late next week. Judging by others' playing times, I have anywhere from 15 to 25 more hours to go. If I make it, it'll probably be close. I'll see how long my second playthrough takes and decide, at that point, whether to continue on or pause and wait until after my vacation for the rest of the story.
Here's a pretty non-spoilery screenshot from my first playthrough: