[njacobs5074]

So being able to read a newspaper will enable you to chat with people whom you're not super close to.

Reading and understanding video games & manga is more challenging in that the way the people speak in these situations is much more informal, i.e. lots of slang.

You won't be able to get to the latter without spending some time on the former because the grammatical structures in idiomatic Japanese are full of contractions that arise from the spoken language.

Just as an aside, if you actually spoke like a manga/game character, you'd definitely raise some eyebrows. Probably not in a good way ;)

[presentation]

Though not verbally, as verbal communication is a separate skill altogether from reading comprehension, especially for a language like Japanese that uses Chinese characters. Your bang for the buck in terms of verbal progress will be very low with the approach the author describes.