Some concepts, especially the one about saving, are kinda hard to understand in the manual. Is this some sort of joke?

It was translated by NIGORO themselves. They have some original Engrish, so that's why it can be hard to read. They don't have the best English around, but it is somewhat charming to read.

You can ask me if you need any help with the game, as well as others here!

I also think the Engrish does give the game a lot of charm, same with drawn pictures (some of them are actually quite helpful). What problem do you have with saving?

I think it's probably meant to be intentional. I mean, in the actual game you have things like a shop run by a ghost girl who yells "Aw hell nah, you gon' get burnt!" if you refuse to buy anything.

Intentional or not I love the manual. Not only is it hilarious but it reminds me of the days when Engrish hilarity could be found in many mid to late 90's SNK games.

I don't disagree with the sentiment, its a fun read - but for a game manual, which may or may not have helpful/necessary information, I would prefer something a little less obtuse. Good translation is expensive, though...