a translation for volume 4 of the joint training camp series has surfaced! it’s possible other sources will upload the audio (edit: AUDIO IS HERE) and translate themselves, but until that possibility, here is an excerpt featuring rinharu — including talk of a certain someone’s birthday and a recurring theme from their duet drama! ♥ many thanks again to the pastebin translator!

Ai: Momo-kun, you misunderstood! Rin-senpai wasn’t talking about Gou-san’s birthday, but Nanase-san’s!
Momo: Eeeh?

(thump)
Rei&Makoto: AAAAH!
Rin: What are you guys doing?
All: Rin!
Haruka: Why are you here?
Rin: You guys weren’t coming, so I went looking for you!

Makoto: And so you came just to find us! Thanks, Rin!
Rin: It’s nothing… And what were you guys doing here anyway…
Haruka: It started raining suddenly, so we came to take shelter.
Rin: Oh, that’s it… Oh by the way Haru, tomorrow’s your birthday right? Too bad the weather is so terrible…
Makoto: It’s fine, it rained so much already, I’m sure it’ll be sunny tomorrow.
Haruka: Anyway Rin, you’re drenched.
Rin: Oh… It started raining suddenly when I was on my way.
Makoto: You should get changed, or you’ll get a cold.
Rin: Why would I have brought a change…
Haruka: I’ll lend you mine.
Rin: Geh! That’s…
Makoto: His Thinlip-mullet-kun T-shirt, huh. (edit: according to this correction, makoto actually says a play on “northern stoplight loosejaw-kun” — the shirt from the rinharu sleepover!)
Haruka: Don’t complain. I only have this one.
Rin: Yeah, guess I’ll be grateful for that. …Oh? Hey, where did Nagisa and Rei go?
Makoto: Oh? They’re here- Huh?
Haruka: They’re gone…

Momo: Aah, I didn’t think it was Nanase-san’s birthday… Ah, but, maybe he likes stag beetles too!
Ai: Huh… Who knows… Oh? Yamazaki-senpai, are you alone? Where’s Rin-senpai?
Sousuke: He left a note. Apparently he went to look for Nanase and the rest.
Ai: Huh? In this storm?
Sousuke: Damn, they’re not kids, he could just have let them be…

— once again, THE FULL TRANSLATION