Are you under a contract? Can't you at least mention the name of the anime and the game's genre?
Perhaps you can make a demo without using the JP talent as marketing but mentioning its based in that anime? Even sharing the demo to the fanbase?
If you are not programmer or artist do not try to use AI. At beginning it may work. But if the project becomes bigger/complex the AI will start to 'lose' or 'confuse'. In programing is better for a quick debugging/asking what X error means.
Can i recomend you try with a low-code engine to create the demo? If the game will be 3D eigther First or third person, narrative or shooter. Perhaps Ambiera Copercube may help you. It's intuitive and really easy to use, you can add different free plugins to increase its cappabilities. (There is a 'toon shading' plugin that may help you give the game an anime look.)
If its a visual novel perhaps renpy or tyrano builder may help.
For art, again,i reccomend you better try with free art (or public domain art) from internet.
Idk. There are several tools and forums thay may help you work alone for now.
By the way. Merry Christmas to all.
:-)