From the Animeraider:

Tsubomi learns that a rumor has spread through her school that Haruyama likes her, which seems improbable as he’s handsome and she’s not very pretty (according to the gossip). She has a stern look, glasses and hasn’t many friends. When Haruyama actually asks her out she believes it’s all part of a cruel joke and calls his bluff and then dumps him almost immediately, just so he can see what it’s like to be treated so cruelly.

Only Haruyama might have been telling the truth…