Recent letters regarding the need for dual citizenship in Japan seem to deal with the practical benefits, real and perceived, associated with nationality. I suspect that for most affected individuals, however, this is a much more emotional matter.
My children are both Japanese and British. As they grow, their emotional attachments, focused initially on their extended families, will also grow to include the language, culture, geography, food, music, art, sport, humor, etc. — perhaps even the political and administrative institutions — of both countries.
Yet, when the young people that these attachments anchor and have shaped reach the cusp of maturity, Japanese law requires that they renounce half of them. My children are not half-Japanese and half-British, but Japanese law insists that, as adults, they can only be half-people.