The social structure and how you view friends or make friends are different in all cultures including Japan.
Japan does not have the concept of "casual friends" or "light hearted friends" in the same way that places like the US have, but more similar to the way friends are viewed in the UK maybe, and friends take a lot of work and time to make.
In the middle of this is that most of your social life and work life are merged into one, which is different to countries like the UK and US, and you will be expected to work very long hours to show your love of the company.
Japan does not have the concept of "casual friends" or "light hearted friends" in the same way that places like the US have, but more similar to the way friends are viewed in the UK maybe, and friends take a lot of work and time to make.
In the middle of this is that most of your social life and work life are merged into one, which is different to countries like the UK and US, and you will be expected to work very long hours to show your love of the company.