Summary
Iroha 2 is a new generation of a blockchain solution, designed for convenient usage in the fintech-related field.
Requirements information
The main source of requirements is Iroha 2 whitepaper, which can be found here: https://github.com/hyperledger/iroha/blob/iroha2-wp/iroha_2_whitepaper.md
Currently (on 2020-05-21), work on the whitepaper is still in progress.
Also, check the "Requests for comments" section to propose or participate in the discussion of particular Iroha design decisions.