>>2943656

The text says "Original childhood friend impregnation book", and the character looks like the girl who appeared at the end of the Hachisaku-sama doijin (pic related).

That said, there's no confirmation if it really is the same girl, and the doujin will be continuation of the boy's story (the same boy who is the brother of Ooya-chan, from her doujin) or if Akuten Soushin just decided to take the character design and make a new character/story entirely.