What are NFTs?

According to ethereum.org - https://ethereum.org/en/nft/#what-are-nfts "NFTs are tokens that we can use to represent ownership of unique items. They let us tokenize things like art, collectibles, even real estate. They can only have one official owner at a time and they're secured by the Ethereum blockchain – no one can modify the record of ownership or copy/paste a new NFT into existence.
NFT stands for non-fungible token. Non-fungible is an economic term that you could use to describe things like your furniture, a song file, or your computer. These things are not interchangeable for other items because they have unique properties."

Why use NFTs for Ukiyo?

The primary goal of incorporating NFTs into Ukiyo is to allow players to establish control over some of the game items that they own. Our main approach is to provide a large, extensive, and feature-rich environment for the effective integration of NFTs and to ensure that they bring utility to holders.

Which blockchain will Ukiyo NFTs be on?

Ukiyo will be running on the Ethereum blockchain. Any NFT collections that are sold before our alpha release will be minted on Layer 1. This allows for a simple minting process because most investors in this market are already familiar with the classic minting technique on Layer 1.
The actual in-game blockchain mechanism will be running on a Layer 2 solution - Immutable X. Immutable X enables instant trade confirmation, massive scalability, and no gas fees, all of which are critical to guaranteeing a seamless backend that supports the game's blockchain capabilities.
More on Immutable X: https://docs.x.immutable.com/docs