Provided this isn’t a goof-up on Bandai Namco’s part, you may need a bigger boat Micro SD Card.
According to Bandai Namco’s Switch game list, they’re showing a notice underneath the listings for Naruto Shippuden: Ultimate Ninja Storm 4 – Road to Boruto on Switch that the game will require at least 40GB of HDD space. This goes for both the boxed edition (top) and digital edition (bottom) it seems.
Also worth noting that Naruto Shippuden: Ultimate Ninja Storm Trilogy (literally containing the first three main games) on Switch in its entirety is only 17.6GB in comparison.
Big credit goes to James G. of RPGSite for verifying the translation for me! 🙂