The depression is coming specifically from lack of time and autonomy by the time they come home (which is very late at night) they're so exhausted from their monotonous repetitive lives that they just want to sleep, which is a problem with most adults nowadays but it's much much worse in Japan because they have no time at all for hobbies or social lives and it's gotten to the point where teens dreading this destiny will end themselves before getting that bad.

For those who don't know this is why most anime take place in high school, that's the last time most Japanese people get to feel relaxed and free and why most Isekai protagonists are middle aged salary men who get reincarnated into younger body's.

Depressed Japanese people reading this: