TASK DEFINITION: In this task, you are given a sentence in the English language and your task is to convert it into the Japanese language. In translation, keep numbers as it is and make it sentence case (capitalize only the first word of each sentence and noun).
PROBLEM: According to Japan's Act on nationality, a non-Japanese child (under 20) who was after its birth legitimated by marriage and acknowledgment can acquire Japanese nationality by filing notification, with some requirements which the plaintiffs had already fulfilled.

SOLUTION: 日本の国籍法によると、結婚および認知によってその出生が合法化された日本人以外の子ども（二十歳以下）は、原告らが既に記入していた通知に記入することで日本国籍を得ることができる。

PROBLEM: Meanwhile, the underlying rate of RPI increased from 3.8% to 4.6% over the same period.

SOLUTION: 一方、RPＩの潜在的な率も同じ期間に３．８％から４．６％に上がった。

PROBLEM: The father, Lam Luong, a 37 year old shrimp fisherman, has been charged with four counts of capital murder.

SOLUTION:
父であるLamLuong、37歳のエビ漁師は4つの死刑に相当する殺人の訴因で起訴されている。