Knowing how barely there have been chapters about the main characters in high-school recently, I wouldn't be too hopeful for a Minato spinoff along the same lines.
For a time‑skip sequel doujinshi that’s supposed to focus on the characters in high school/around age 17, it really hasn’t spent much time on that lately. The actual high‑school content feels like the minority at this point..
Bro... You can't just leave information like this without providing a link or concrete proof of what you said. I can't find anything recent about this manga on the artist's Pixiv or the actual website. Where are these "plenty more chapters"? 😭