The Practice Ground belongs to Ono No Takamura, and gives Musashi a place to hone his skills or refight bosses outside the flow of the main story. It can be reached by ringing the bell at Rokudo-chinnoji Temple or, more directly, by fast travelling there from any unlocked Spirit Mirror.
Drills
Drills let a player practice the techniques already learned over the course of the adventure. The available drills expand as new abilities are learned through Equipment Enhancement, so the Practice Ground grows alongside Musashi rather than staying static.
Boss Rematches
Boss Rematches pit Musashi against any boss he has already defeated in the main game. The rematch can be made harder by raising the difficulty level and by raising the boss's own stats, giving a way to test refined Combat System skills against a familiar opponent under tougher terms.
Rules for Rematches
No items may be used during a Boss Rematch, with a single exception: Hozuki, used from an equipped Hozuki Pouches, remain available. This keeps rematches focused on combat execution rather than item stockpiles, since raising the boss's stats already makes the fight tougher than the original encounter without additional item support to compensate.
Why Visit the Practice Ground
Because rematched bosses can have their stats raised on top of a harder difficulty setting, the Practice Ground works as a genuine test of a build rather than a victory lap against an already-beaten opponent. It is also a low-risk way to try out a newly learned ability from Equipment Enhancement against a known attack pattern before relying on it during an unfamiliar story encounter, and a way to sharpen reaction timing on Break Issen and other Issen-family techniques without the pressure of losing story progress.
Ending a Session
A Drill or a Boss Rematch is ended from System Menu > End Practice, which returns the player to boss selection or drill selection before exiting the Practice Ground entirely and heading back out into Kyoto.