I'll keep this review short just like this drama...
This drama is first of all a prequel drama to a movie, which is pretty common in Japanese film industry for some reason (eg.- Gokusen, Are you ready? Hey you girl and L DK)
Secondly, it's pretty cliched. Girl sees someone getting bullied. Girl stands up to said bully. Bully turns out to be the most popular guy on campus. Bully starts harassing the girl as revenge. Bully's Bff saves the girl. Girl develops crush on Bff. Bff is in love with someone else. Girl gets dejected. Bully shows a little sympathy. Girl starts liking Bully (Masochist). Bully still harasses the girl but also starts liking her (Sadist). Bff gets rejected and realises he might actually like Girl. Bff starts chasing girl. Bully starts chasing Girl. Girl gets conflicted. Ends on a cliffhanger. (starting point for the sequel)
If you are wondering why this plot seems so familiar, it's because this is almost the same exact plot as Boys Over Flowers/Hana Yori Dango/Meteor Garden (even the color theme is similar. The main lead has dark hair and mostly wears black clothes, the 2nd lead has bleached hair and predominantly wears white attire).
So yeah the story is not unique. But the overall character development achieved is pretty good. Unlike Boys Over Flowers where the FL always helps the ML with his character development but the vice-versa never happens, here both the leads as well as the other side characters help with each others improvement.
In conclusion if you wanna watch a great Japanese drama I would suggest you keep looking but if you wanna watch something for passing the time this drama is a fun watch.