This is definitely a good decision. Don’t use literal image from the anime itself.
That’s okay, there’s games like Blox where you can obviously tell their inspiration but they’re still up because they don’t use specific textures, music, etc. A blocky, procedurally generated game is not copyrighted.
To answer your question, try to avoid proper nouns and instead encapsulate the general idea. Don’t use the word Bleach, Cero, etc. and find synonyms.
