can i become a mangaka?

I have aphantasia and I draw as a hobby. It won't stop you from being an artist. Just read lots of manga and draw. A million people have said this before, but practicing is the best thing you can do. Just don't give up on it. Best of luck to you! : )

While you don't absolutely need a degree to be a mangaka, formal education can help give you the professional skills you need. A bachelor's degree in fine arts is a good choice, as it will help you build up your artistic skills. However, you can also go much more specific.

10,000 hours to have one of the worst-paid and stressful jobs in the comics industry.

Honestly, I don't see why you should.  Do you? 

i dont see why not