To manage character information in unity

Please accept it as one solution.
Answer with the assumption that you will use Json.

Place a directory directly under Resources to store data and

{
    "id"—1,
    "name": "instant",
    "detail": "Young Agent of Celestal Being",
    "name2": "Gundam",
    "atk"—1000,
    "hp"—1000
}

It creates a data structure like this.
You can retrieve data using Resources.Load.
It's the same when using a server, and the server side converted the data to Json.<> I think you can design it accordingly.
You will need an ID in the future, so I think it would be better to set it up.

Also, if you parse this Json data and make it into a class or associative array,
I think I can design it flexibly.

If you want to be able to see it in the inspector, you can develop your own Editor and
Prepare your own GUI.
*It should not be so difficult if it is implemented along with data reference.

I hope this is the answer I was looking for.

I've never touched Unity, so I don't know if it's possible, but I think it's better to manage simple metadata in a file.Of course, DB is fine.
The data structure of the file is JSON, XML, Yaml, toml, CSV.If you have any ideas, you may want to think about how to save the data yourself.