Upon entering Tsuta Ruins, ignore Issun's suggestion of trying to use Water Lily in the poisonous water, as the poison will immediately dissolve the lilies. Head left, Power Slashing plants on the way for food (or Yen, if Amaterasu already has a full Astral Pouch), examining the Blockhead's back at the end. Don't forget to bloom the Giant Bud on the small island near the Blockhead. Then head right, chopping the vegetation on the way, remembering to bloom the Giant Bud (contains a Traveler's Charm) and the treasure chest in front of the door to the next room (contains a Vase). In the next room, simply apply the normal tactics for Cursed Trees to purify the ones here. Note that on the small island in the waters, there is a Clover. The door to the next room is on the other side of the walkway. In the next room, bloom the Giant Bud at the end of the corridor for a Incense Burner. Jump on the ledge, then leap to the small ledge on the right, reaching the second level of the room. At the end of the escalated platform, there is a Clover. Back at the ledge where Amaterasu jumped onto the second level of the room, ahead is a pool. Use Water Lily to climb the ledges on the other side.
Once atop the ledges, notice the immobile spherical stone and the strange fruit-like thing ahead. Move closer to the thing, and it reveals itself to be a Bud Ogre. See the link for strategy of defeating this demon. After killing the demonic plant, the spherical stone is revealed to be a sphere. Roll it down the slope to a pressure pad, opening the door on the side. Remember to destroy the statuettes at the end of the corridor. In the next room, two Bud Ogres will be battled. Kill them to reveal some mushrooms, then span the camera up to the broken ceiling and use Sunrise to make the mushroom grow (which is not something that happens in reality). Leap on the makeshift platforms up to the ledge above. In a section of the wall near the ledge, where the wall is pulled back but doesn't have a crack, use Cherry Bomb on the wall to open it and follow the path to a Clover. Back at the main path, follow along, and use Cherry Bomb on a cracked wall to open it. Get through the door at the end of the room to access the next room, which is actually a bridge above the room to the right of the antechamber of the ruins. On the other side of the door that is at the end of the bridge, Amaterasu will be back at the antechamber, but on a walkway at the back behind the Dogu statue and high above the poisonous water. However, Issun will sneeze because of the giant mushrooms earlier, causing the walkway to collapse. Immediately dash to gain speed, then rush to the other side.
Once Amaterasu has got away from the collapsing walkway, get through the door. In the next room, get to the other side of the bridge with a Lockjaw blocking a door, then carefully jump from where Amaterasu is standing onto the lower platforms on the right. On the second platform jumped onto, it is noticeable that the wall behind the statuettes is different from the normal wall. Place a Cherry Bomb to blow that wall open, revealing a secret room with a Giant Bud that yields Stray Bead #18. Now, jump down to the bottom of the room and face the Blockhead there (the one facing its back to the left entrance of the antechamber). Headbutt it, causing it to reveal its 2 weak spots, the dot the Celestial Brush on those dots do kill the Blockhead. If Amaterasu fails and redoes the sequence, the pattern of the dots will be different. After killing the Blockhead, an Exorcising Arrow and some tree trunk ramps will appear. Grab the arrow, then follow the ramps up to the bridge above to the Lockjaw. The arrow will kill it, opening the door. Pass the door.
On the other side of the door is a room with an Origin Mirror and a Blue Demon Scroll. Behind the mirror is an alcove covered in vegetation. Power Slash those plants for food or yen. At the end of the room is a broken bridge that is above the entrance of the Tsuta Ruins. Use Rejuvenation on the bridge, and get to the other side. Cross the door on the other side of the empty room to access a room with 3 Devil gates. Complete those gates, and another patch of mushroom will grow. Use Sunrise again, then leap up onto the ledge alongside the room. Follow the ledge to where 5 urns of poison sit and poison Tsuta Ruins' water source. Destroy these urns to restore the water source and clear the ruins of the poisonous water and get the Tsuta Ruins Map in the treasure chest nearby. Jump down the waterfall to the small stream that flows on the side of the room. Behind the waterfall is another secret room with Stray Bead #19. Jump down the larger waterfall at the end of the stream down to the antechamber.
When Amaterasu plummets down the waterfall, align so that she lands on the left of the waterfall, on a small alcove with a Clover. If she failed, reach the alcove with Water Lily. The entrance to the Dogu statue in the center of the room had opened because the poisonous water has cleared, so enter it. Inside, bloom 3 patches of dead grass, and Tsutagami will appear, granting Amaterasu Vine. Try out on the Konohana Blossom in the center of the room. Then, get out of the statue by the front entrance and through the door on the far left where the first Bud Ogre is fought (where an immobile sphere is used for a pressure plate). There, look up and a Konohana Blossom will be seen. Use Vine to reach it, and there, a Giant Bud will be found, containing Stray Bead #20. Anyway, return to the antechamber, then use Vine on the Konohana Blossom in front of the Dogu statue. Jump on the path that surrounds the midsection of the statue, then move along it to some Konohana Blossoms. Use them to get onto the top of the statue. There, use the Konohana Blossoms on the hooks of the lid to lift the lid up, revealing the entrance to the inside of the Dogu's head. Save, then venture through the tunnel to a large chamber containing 2 treasure chests and some skulls. Up the stairs in the room is a door. Past the door is a Golden Gate and up ahead is the first boss battle.