How is it that a full Japanese girl could have blue eyes?

Question

I met a girl recently, who was full-blooded Japanese, but had completely black hair and bright blue eyes.

How could this be? She insisted she was 100% Japanese.

What would cause a full Japanese girl to have blue eyes?

Thank you.

Answer 1

She could have adapted a blue eyed gene somewhere down the line. Its very rare, but it has been known.

Answer 2

she could be a chimera, meaning she has two sets of DNA, but this would imply that she had a western parent somewhere down the line.

or she could be wearing blue contact lenses

Answer 3

Her father had blue eyes.

To have blue eyes, your father must have had blue eyes.