After watching Extraordinary You for the second time,  I came to realize that Haru never goes somewhere to sleep. Compared to Dan-oh who goes home and sleeps in a bed, Haru is only ever at the school and library. Does he sleep there? Where does he get his clothes? 

Does it say something about this in the webtoon? It's just been bothering me for the second watch in a row.

I  haven't read the webtoon and I think this might just a plothole but here's my guess:

since Haru isn't a character at first and then just an extra, the writer couldn't be bothered to write a background for him (no parents, house etc.). Haru, unlike other figurants does have an ego, so he doesn't just mindlessly leave the school grounds at night, but stays there. So, yes he sleeps at the school. 

In episode 10 (party episode) LDH mentions that he made Haru wear a suit from his brother, so everything he wear that isn't his school uniform is borrowed, until he becomes an extra and the writer draws his outfits for him.

 Anastasia:

After watching Extraordinary You for the second time,  I came to realize that Haru never goes somewhere to sleep. Compared to Dan-oh who goes home and sleeps in a bed, Haru is only ever at the school and library. Does he sleep there? Where does he get his clothes? 

Does it say something about this in the webtoon? It's just been bothering me for the second watch in a row.

The actual reason is that in the webtoon there's no night, the characters don't sleep, except for a room in Kyung's house nothing regarding the other people's house is shown. In the drama, lots and lots of things were changed. I'm sure they didn't even think about this but Ha Ru is shown drawing in the library at night in the drama.

I hope this was a bit helpful.