Well shit... I don't own a DS myself, I can borrow it off my friends but there lies the problem, I live in Hong Kong and AFAIK the DS is region locked, all my friends have the Japanese DS which presumably can only play the Japanese version of 999, unfortunately I don't speak Japanese.
How about just watching a YouTube playthrough of 999? Would that be enough?
Sorry for going off-topic.
The standard DS is not region locked, only 3DS consoles. You should be good with a Japanese DS if you can get your hands on a copy.
A YouTube playthough would be a last resort thing. If it were any other game I would tell you go right ahead, but without revealing spoilers, there are moments in 999 that are simply not possible on any medium but a physical DS console.