NARUTO: Konoha Shinden - Yukemuri Ninpouchou

The novel has three protagonists—Guy, Kakashi, and Mirai—and takes place at a hot spring. The novel "ties together Naruto and Boruto," and is set between the final chapter of the original Naruto manga and the Nanadaime Hokage to Akairo no Hanatsuzuki spin-off manga.
(Source: Anime News Network)
Note: Adapted into the Steam Ninja Scrolls arc in the Boruto anime, consisting of episodes 106 to 111.