It's a sequel*, check the "related" tab
* It doesn't feel like a sequel for now since we're back at the beginning with another pov, but wait and see I guess
Not another sequel, but another route with Hinami as the heroine, not Misaki. This manga is based on a visual novel, which has 4 routes. Misaki, which was already completed, Hinami, the one we're reading right now, Nanase, which will most likely be covered in the anime adaptation, and Fumino, the route considered to the true end of the game.
However, you could consider it a pseudo sequel to the Misaki manga adaptation, where the author takes into account that you've already read the first nukitashi manga before diving into this second nukitashi manga. Whether the author will re-explain everything or not, we'll have to see. But if he doesn't, consider this manga to be a pseudo sequel to the Misaki manga.
As a funny aside, I'm currently reading that Fumino route rn as I'm writing this. Hahaha, what are the odds that as I'm taking a short break from the Nukitashi game, I somehow start reading a just released Nukitashi manga chapter. In other words, taking a break from playing Nukitashi to reading Nukitashi manga, truly a coincidence of all time hahaha.