How to Buy a Friend

Chan Hong is an ordinary high school student. One day, his teacher suggests that he enter a writing contest. At first reluctant, he later signs up when he discovers that his crush, Sae Yun, is also in the contest.

Sae Yun recognizes a sentence from Chan Hong's poem. As Sae Yun did, Don Hyuk also realizes Chan Hong's poem and remembers seeing the sentence from the text message sent by Seo Jung before. A bully beats Chan Hong up after things didn't turn out so well with Sae Yun. Don Hyuk offers Chan Hong help, and Chan Hong cries out for help.

Don Hyuk offers Chan Hong protection from Dae Yong if Chan Hong agrees to tell Don Hyuk what he remembers about Seo Jung, but Chan Hong turns down his offer. Some people start to track down the person with Seo Jung's cell phone. A mystery woman visits the school and meets Sae Yun and Mi Ra.

Dae Yong threatens Sae Yun in a bid to see if she has Seo Jung's cell phone. Chan Hong couldn't just stand by while she was being harassed, so he takes Don Hyuk's offer and asks for his help. Sae Yun hands Seo Jung's phone to Chan Hong, but he decides to keep this secret from Don Hyuk. Chan Hong, Kyung Pyo, and Don Hyuk go to Seoul to find the man who Seo Jung met before she died.

Chan Hong and Don Hyuk end up at the police station. Chan Hong's parents take Don Hyuk with them. Chan Hong explains how he got Seo Jung's phone to Don Hyuk. Meanwhile, Mr. Woo gives Seo Jung's poem and writing to Chan Hong. As Chan Hong reads Seo Jung's writing, he figures out that something is different from the post on the dating board.

Chan Hong, Don Hyuk, and Kyung Pyo steal other students' writing to compare them with the post on the dating board to find out who really wrote it. Cho Pyung Seob and her boys are still after Seo Jung's phone. Mi Ra attempts suicide and is transferred to the hospital. Don Hyuk and Chan Hong find the street related to the sentence that Seo Jung sent to Don Hyuk.