First two eavesdrop conversations are only available until you enter the tower.
Ashina Soldiers (gatehouse)
"The moonlight shines .."
Look up while crawling under the shack.
Ashina Soldiers (main area)
"The Moon-view Tower door .."
At the foot of the stairs leading up to the tower.
Moon-view tower
Decide what to do with Kuro's Charm
Giving it to Kuro will make the game harder, but increase rewards. You can get it back at any time by talking to the Sculptor.
Ashina Soldiers (bridge)
"You know the secret passage .."
Reservoir
Finishing the prologue moves you to the Dilapidated Temple.
Sculptor's Idol (Ashina Reservoir)
"Heard reports of a shinobi .."
Well
In and around the well that you start the game in.
The path at the back of the well leads to the Bottomless Hole area of the Abandoned Dungeon.
Main area
Under the gatehouse.
Gatehouse
Moon-view tower
Grapple up the outside of the tower and go around to balcony at the back of the tower.