Volume 4 just came out in English.
Speaking of volumes, there are two bonus chapters that haven't been posted on this site. I'm including a brief summary of what happens in each- there aren't any spoilers, but they help flesh out some secondary characters.
Chapter 4.5 is a bonus in Volume 1. Shiori gives Kaori the morning glory seeds, and Kaori says she'll give them to her "friend"(Shizuku, obviously) whom Shiori knows Kaori has been seeing every day. Shiori is a bit worried about Kaori, but Kaori reassures Shiori that she's having fun. Shiori decides to let Kaori spend time with her "friend," but insists that Kaori spend time with her, too.
Chapter 9.5 is the first time Ruri and Seri are shown after the flashback. Seri greets Ruri at the station, and it's mentioned in passing that the reason why they wear their uniforms is because they have club activities over the summer. Seri considers getting dinner with Ruri, but Ruri flinches when she sees that the place is a curry place, a "show don't tell" way of revealing that she's still traumatized by Shizuku's bullying (in the localization of Chapter 14, she says to Shizuku, "You made me hate something I liked," implying that curry triggers her trauma). As they walk away, they get a text from Kaori.
There are a few other bonus illustrations, such as Kaori wearing Shizuku's jacket, or the two dressed as butlers, with Kaori standing on a stool to be on level with Shizuku's head.