Boruto: Naruto Next Generations' time travel arc has shown Boruto a whole new side to his father. Who he thought was strong and collected before as the current Hokage of the village was actually a boy who was struggling to get noticed by those around him, and had trouble doing the kinds of jutsu he can do with ease as an adult. Jiraiya had tasked Boruto and the young Naruto with training toward a combination jutsu, and this has brought Boruto even closer with his father than ever before his new level of understanding is reflected in this new jutsu.
Episode 133 of the series sees Boruto and the young Naruto's increased unity showing in a different way as the two of them advance further in the mastering of his combined Rasengan. Now the two of them can sync their chakras better than before, and are closer than ever to a point where they can use it against Urashiki.
After reconnecting following their brief fallout in the last episode, Boruto and Naruto continue their training to swirl the Rasengan within a rubber ball. Boruto has trouble syncing his chakra with Naruto's at first, but Naruto devises a new way to help him focus. Drawing a Hidden Leaf symbol on Boruto's hand, this gives him a better point to focus and the two advance their jutsu further.
As the two of them try to swirl their chakras once more, the rubber ball begins to expand to a size they had yet to get it to. But before they are able to complete the training, the two of them run out of chakra and call it quits for now. But with the advanced level of the jutsu, maybe now they'll be able to put it to practical use now that Urashiki is attacking once more at the end of the episode.
Originally created by Masashi Kishimoto for Shueisha's Weekly Shonen Jump in 1999, Naruto follows a young ninja, with a sealed demon within him, that wishes to become the leader of his home village. The series ran for 700 chapters overall, and was adapted into an anime series by Studio Pierrot and Aniplex that ran from 2002 to 2017. The series was popular enough to warrant a sequel, Boruto: Naruto Next Generations which is set several years after the events of the original Naruto story and features the children of many of its key characters such as Naruto and Hinata.