What would you do if you suddenly lost your ability to read, and the text you're reading now became an incomprehensible jumble of letters?

That's the world Keisuke Shimakage's father faced after he experienced a stroke in 2012. Since then, Shimakage, 26, has been working to develop a product that helps patients like his father by using his own expertise — product design mixed with digital technology.

"Perhaps it's difficult for us to imagine a world where things you were able to read before become suddenly incomprehensible. We forget about the days when we were unable to read, before growing older and becoming literate," Shimakage, CEO of Tokyo-based startup Oton Glass, said during a recent interview with The Japan Times.