After leaving Kamiki, Issun will comment about the bleak state of Shinshu Field. Entering the main span of field, the first thing should be done is entering some Demon Scrolls and farm them to get prepared. After enough farming had been done, head north toward the large cave with the contaminated stream running out. Beyond that cave is Hana Valley. Enter it.
After entering Hana Valley, run toward the treasure chest on a small island that contains a Traveler's Charm. Then, approach the imps who are having a party. Approach closer, and they will notice Amaterasu and attack. Just kill them with farming, as it is more recommended. A small island will briefly appear, but it immediately vanished. Proceed to the other side of the tunnel. Near the first tree on the left is Stray Bead #11, the only Stray Bead of Hana Valley. Proceed forward, and when crossing Cursed Trees, use Power Slash to deflect their fruits back at them, temporarily stunning them. On the other side of the bridge are more Cursed Trees, and at the end of the path, Amaterasu will enter a cave. There, she will encounter a Yellow imp. After killing it, Susano, who had been trying to move the boulder in order to access his hiding area, finally notices Amaterasu's presence and after a conversation, move close to the mural on the wall to the right. At the upper right corner of the mural, the sun is missing, so use Sunrise to restore it. Restoring the mural has a suprising effect: the boulder blocking entrance to Susano's hiding area is destroyed, granting access to said area.
In the tunnel, jump on the walls and enter a small clearing with a tiny Guardian Sapling sprout. On the left is a path blocked by wooden rods; Power Slash them away. Proceed through the path and enter another cave with Susano and a bear inside. After a monologue with himself, Amaterasu has to assist Susano in slashing the four torches around the cave, and finally, slashing at the bear. After the "Susano Style" technique is finished, the so-called warrior will finally notice Amaterasu. After he ran off, roll the crystal Sleepy had been standing on back to the clearing outside, and up onto the altar, then roll it into the small pool there. Then, use Sunrise on the sky above the waterfall, which then sunlight shines down on the crystal, and the object focuses the sunlight onto the small Guardian Sapling sprout and it grows into a fully mature Guardian Sapling (yet still withered). Another suprise: when the Sapling had fully matured, Sakigami's constellation appears. Fill in the two missing stars and the first flora god grants Amaterasu the Celestial Brush technique of Bloom. Use it on the Guardian Sapling and the entire of Hana Valley will be rid from the curse. Exit the cave.