Go back to the story. Kashiwa is Daimyo Oak and see all over Japan. Oak leaves, until the sprouts grow from old leaves fall, fartility are said to be carrying a good luck.
Some places use leaves of China root.
We also have sakura mochi which is mochi with cherry leaves in Japan. This is our culture.
Mochi is meade from sweet rice. It is same cooking as regular rice and pond and make sticky.
Then, stuff braised sweetened red bean. This is called anko. An pan is bread with anko.