Legitimate; orthodox; traditional — indicating something is rightful, formally recognized, or the main/traditional line.
彼は王位の正統な後継者とみなされている。
He is regarded as the legitimate heir to the throne.
この作品はシリーズの正統な続編だ。
This work is the official/traditional sequel to the series.
学問の正統な方法論を学ぶことが重要だ。
It's important to learn the orthodox methodologies of the discipline.