Momoyama (桃山) is a baked wagashi (traditional Japanese sweet) that’s similar to manjū.
The difference is that momoyama uses white bean paste (shiroan), not only as a filling but also in the dough itself.
The other ingredients used are egg yolk, sugar or mirin, and a type of glutinous rice flour called mijinko.
It’s said that the name comes from Momoyama castle (also known as Fushimi castle) in Kyoto.
By the way, this castle was famous for its golden tea room.
The original golden tea room doesn’t exist anymore, but there are replicas available.
The initial shape of this sweet was similar to the roof tiles of Momoyama castle, hence the name.
Here’s a video with the recipe: