LogFAQs > #980032798

Hakusho pretty clearly means report, file, log, document, record, etc in this context. It's what they call government papers in Japan. And Yusuke is supposed to be a detective so that's pretty obviously what it means. "White paper" and "white book" make zero sense to say in English.

The first is probably rei, but it's unclear what the second is. I don't think it's gi, though. Maybe it's ryou; Yuuryou/ means means "recreational hunting" or simply "hunting".

Yuurei = Ghost
Yuuryou = Hunting
Hakusho = Report(s), file(s), document(s), log(s), record(s), etc

Still it's never been confirmed what the stars mean so this is ultimately guesswork. The first yuu means dark, hidden, gloomy, underworld, netherworld, etc. The second yuu normally means play in Japanese but since Saiyuki (Journey to the West) was the original inspiration, it's probably the Chinese meaning, which is traveling, wandering, visiting, moving, going somewhere, coming from somewhere, etc. This is also backed by the fact Yusuke becomes a wandering ghost at the start of the series and/or the fact he faces other wandering ghosts.

The basic meaning is "report on things coming from the underworld" or "report on things going to the underworld" and there are really so many things that you could come up with to convey those meaning. I'd just go with Ghost Hunting Files, honestly. Or Ghost Hunter Files. Or just Ghost Hunter. Or Wandering Ghost Files. Or maybe Ghost/Spirit Detective (what Yusuke is called in the series)?

Ghost Files and Ghost Fighter were totally fine titles, honestly.