Learning English is very challenging but can be done. The most successful way to do is to keep things fun at all times! I speak 4 languages, so I know how to learn/study languages well. I promise that you will be able to speak good enough within 5 months！
If you wanna study for the TOEIC, I can teach you some techniques and help you get a great score. If you are interested in English conversation, I'll be happy to help you, too. If you are a beginner, I can teach you English by explaining in Japanese.