In so many animes, I have noticed that middle- and high-school kids live by themselves without any adults around to supervise. While this may serve as a useful plot device, I noticed that it happens far too often. Arima Kousei of Your Lie in April lives alone because his father is always out on business trips, Sakuta Azusagawa (Rascal Does Not Dream of Bunny Girl Senpai) and Kyon (Haruhi Suzumiya series) live with their younger sisters. Other characters of Haruhi Suzumiya like Yuki Nagato and Ryoko Asakura, both functionally human to that society, also live by themselves. Is that common in Japanese society?
[Having lived in multiple cities across multiple countries, I have never seen school kids living alone in houses like that. The best I've seen within the budget of older university students are single-room apartments or shared houses.]
Ideally, I'm looking for answers from people who have first-hand experience of school life in Japan. Answers based on studies and reports would be OK too, if you can translate the relevant information to English.