Some more information came out about how you will raise Trooper Cards and level up equipment in Like a Dragon: Ishin. Trooper Cards are a new combat mechanic that Ryoma Sakamoto can use. They can directly damage or debuff enemies, as well as buff Ryoma. [Thanks, ryokutya2089!]
You can combine different Trooper Cards for greater effect. For example, Shinada’s Trooper Card ability slows down time, whereas Haruka’s Trooper Card ability will guarantee that all of Ryoma’s attacks land a critical hit. However, because Haruka’s ability is only effective for a short amount of time, you can combine her with Shinada to make more use of it. If there are Trooper Cards you do not need or have duplicates of, you can feed them to ones you want to keep to level them up. So building and levelling up your deck will be the key to success in Ishin.
Here is a trailer of how the Trooper Cards will work in Like a Dragon: Ishin:
As for the equipment that you can give to Ryoma, there is a skill tree system to upgrade them. You can use a variety of materials to boost their stats. Each equipment also has slots that you can put seals in to further enhance them. It works similar to Materia in Final Fantasy VII.
Like a Dragon: Ishin will come out on the PS4, PS5, Xbox Series X, and Windows PC on February 21, 2023.