Quick thoughts:
Why do Japanese people use Twitter more than Facebook?

If you compare Facebook and Twitter, Facebook is a much more vain social media website. Facebook is about the humblebrag (subtly letting others know how amazing your life is – or how amazing you think your life is), whereas Twitter is less “in-your-face”. Maybe because, even though there are more tweets per minute than Facebook posts, this causes the minimal characters to become camouflaged. Twitter lets users self-efface, meaning it allows them to not draw as much attention to themselves; masking yourself. In Japanese culture, one of the major offences is to be ego-centric and self-centered. This could be the main reason why Twitter is more popular in Japan than Facebook is. It may not be a conscious thing that people thought about when deciding which social media to sign up for, but the fact that it has been embedded into their philosophy for hundreds of years, it becomes their natural instinct and a mindset they are immersed in.