TOKYO - What underpins the legitimacy of the imperial family's role and imperial succession? The system involves male-line male descendants of the former 11 collateral branches that left the imperial family after the war. I do not reject adoption itself as a way to secure the stability of the imperial family. What became clear, conversely, is that unless Japan settles the imperial succession issue that was shelved this time, the future of the imperial family will be precarious. It makes sense to apply it starting with female members of the imperial family born in the future.