Why do some girls like Oikawa? In the anime, Oikawa is popular with girls despite being arrogant, conceited and haughty, yet his skill is far from Karasuno's setter. Some girls in the show even shout and cry when he appears.

Why do some girls like Oikawa?
It's true that Oikawa sometimes becomes angry and he is also arrogant, but these things exist because he is very serious about volleyball.

But why girls like him?

Well, in short, the real reason behind this is because he is attractive.


Many others find him attractive — to the point where several girls follow him around just to talk to him. - Wiki
He is the captain of Aobajosai's volleyball team (which is in top 4 ranking) and is widely regarded as the ace setter, so it's obvious that he is popular among students.
Oikawa has a good sense of his surroundings and can effortlessly read others. 
Flirtatious nature (he is quite famous amongst female students, much to Tanaka and Nishinoya's envy)