"Dzień, w którym Naruto został hokage" is a 17 page long manga-omake included with Zai no Sho. It shows Naruto Uzumaki's Hokage inauguration. The omake is set to be adapted into an OVA that will be included on the limited edition DVD and Blu-Ray releases of Boruto: Naruto the Movie on July 6, 2016.
It's the day of Naruto's Hokage inauguration, but he hasn't woken up yet. Hinata asks Himawari and Boruto to wake their father up, and after Himawari's gentle attempt didn't work, Boruto wakes Naruto up by jumping on him. During breakfast, Naruto wonders if his Hokage cloak will look as unfinished as Kakashi's, since the seamstress hasn't finished it yet. Hinata leaves to get the cloak, while Naruto is supposed to go straight to the Hokage Office with Boruto and Himawari. However, when Hinata arrives there, she finds that her husband hasn't arrived yet, so she runs home. Meanwhile, Naruto wants to leave, but Boruto and Himawari fight over a teddybear until it rips. A visibly upset Himawari turns around with the Byakugan activated in both eyes and attacks her brother, who falls down on the floor. Naruto runs towards them, telling them to stop fighting because they have to go, only to be hit by Himawari's finger. At the same time, Kakashi and Shikamaru decide not to wait for Naruto, instead they ask Konohamaru to take on Naruto's appearance and the inauguration begins. Because Himawari hit his tenketsu, the real Naruto has been knocked out and is found by Hinata, who wonders who could've done that. Meanwhile, a terrified Boruto hides from his sister who enters the room with a demonic expression on her face, asking if Boruto was playing hide and seek.