Here you can find all steps needed to complete both quest lines in Ancient Cultures: Japan.

<color:ffff00ff>Always read your current journal for specific instructions!<color:ffffffff>

Ninja Journals:

1A-1I: Find map pieces around the village and then inspect a geyser.
2: Take the rock sample to the cave north behind Misty Falls. Complete the puzzle.
3: Cross Cloud Gorge to get to Mitsuhiro's Manor. Sneak into the manor without being seen!
4: Go to the Fuji Temple to disarm the explosives!
5: Grab the katana!

Samurai Journals:

1: Go to Elder Shinobu's Home and find the mirror. (Need 2 people)
2: Go to Alchemists cave and find the mirror. (Need 2 people)
3: Go to the Elder Circle and find the mirror. (Need 2 people)
4: Grab the last mirror!
5: Go to Mirror Cave inside Fuji Temple. Place the mirrors and enter the Heart of the Mountain.
6: Grab the Naginata!