So... is Babel Nisei (2001) finished or not?
NO, it is not finished.
Why?
The anime finished after the manga:
Anime finished: December 28, 2001
Manga finished: November 12, 1973
... But MangaUpdates contains information about the anime adaptation and indicates that it is incomplete.
Watching Order (by release date)
Here you have all the anime relations we detected ordered by release date, so you can see the reason for this status in context and also use it as watching order.
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Synopsis
Kouichi, an ordinary student, discovers he's the reincarnation of an alien protector destined to defend Earth.
He joins forces with three super-powered alien allies.
Together, they confront a malevolent cult leader and his dark forces.
Their battles span diverse locations, from deserts to Manhattan and the Swiss Alps.
Kouichi must master his psychic abilities to defeat the enemies of humanity and save the world.