Make the sentence fluent: According to Japan's Act on nationality, a non-Japanese child (under 20) who was legitimated by marriage and acknowledgement can acquire Japan's nationality by filing notification, with some requirements which the plaintiffs had already fulfilled.
According to Japan's Act on nationality, a non-Japanese child (under 20) who was legitimated by marriage and acknowledgment can acquire Japan's nationality by filing notification, with some requirements which the plaintiffs had already fulfilled.