Hirata Estate is one of the optional areas that you’ll encounter in Sekiro Shadows The Twice, and unlocking this area will get you some valuable loot.
After Sekiro’s introduction, you’ll find a special Buddha statue, proceed until you get to the second sculptor figure in the Ashina Outskirts.
After you encounter several enemies, you’ll find a ruined two story building. Go to the upstairs and talk to the old woman there. From her you’ll get the Young Lord’s Bell Charm. Now go back to the sculptor and place the bell in front of the Buddha statue. This will transport you to the past, where you can reenact the events of three years ago on the Hirata estate.
You should travel around the Hirata estate parallel to the Ashina area. Here you will find a hidden temple key, three prosthetic modules and memory that are extremely helpful later in the game. There is also a very special dealer with rare items.
In addition, there are dozens of valuable items here that are worth to keep in your inventory. Here, after defeating several bosses you will receive new prayer beads. The events on the Hirata estate are also significant to the history of Sekiro.