ye, toward the end the series got quite a-bit darker i think
even-tho initially that might not seem like there is a-lot of story for that, i think that when u see the last few episodes & so-on u might notice that the series has a sort-of coming-of-age theme to that. that's abt growing-up & stuff. wot's kind-of interesting is that i think the series in-universe time-line is almost similar to the real-world time, 3 years go by in-universe from beginning to graduation and the series lasted like 3 & a half years or so in real-time, so that might feel like growing-up with them.