Hozuki Castle is a prison run by the Hidden Grass, well known for being notoriously difficult to escape from. Boruto and Mitsuki are sent there to protect Kokuri, a former member of a brutal band of robbers known as the Mujina Gang who's now targeted by assassins after betraying and deserting the gang.
The Shinobi Prison: Hozuki Castle
 
 

سجن الشينوبي: قلعة هوزوكي
Das Shinobi-Gefängnis
– Schloss Hozuki
El castillo Hozuki, prisión shinobi
El castillo Hozuki, prisión shinobi
La prigione dei ninja:
 Il Castello di Hozuki!
Prisão ninja! O castelo Hozuki!
Замок Ходзуки: 
тюрьма синоби