[mtlmtlmtlmtl]

It's perfectly possible to learn a language in 6 months if you spend a lot of your time conversing in it, avoiding English as much as possible. They also said "speak", not "write". It's possible and even natural to learn one and not the other.

[petodo]

Almost anything is possible, even time travel, it's just not very realistic under certain circumstances. In case of learning Japanese in 6 months while working full time in English speaking enviroment with 0 Japanese foundations to start with.