A question regarding my run in Sotn.

Dk what to tag this exactly.

But I started recently on the mobile port, and thought Maria and Richter were the main playing modes as the game just tells you to type either of their names to play the game. But I knew beforehand that we could play Alucard.

I thought first I had to finish a run with either Richter or Maria or something to unlock him.

But it turned out all I had to do was name myself something else apart from "Richter" and "Maria", who are actually apparently additional alternative modes. But since they were there from the beginning I thought they were the main ones.

I'm in Inverted Castle with Richter and have explored much of it.

So how do I go about playing the game in the proper way as Alucard? Do I finish the game as Richter or something? And then start a save for Alucard?