The music getting a little muffled as you go into the cave is a nice touch. The art's wonderful too! I love the texturing on Akyuu's dress in particular.
My biggest criticisms are that the collision and jumping could be tighter, and that Akyuu and the camera moves just a biiiiiiit too fast. Sometimes in the caves I would slide off platforms after moving just an inch.
I really like how items work in this game. Some items changing, like the seed, or marking a pitfall when you die is clever. The frequent checkpoints make it so that dying doesn't feel as frustrating as it could have felt, but the item interactions still give it a purpose.
I can see someone having a lot of fun trying to shave down their number of deaths to the necessary minimum. Me on the other hand, I fell almost 100 times! :P
Good work, thank you for the game! :D