See also: ef - a tale of melodies (Season 2)
ef - a tale of memories focuses on two main characters, Hirono Hiro and Asou Renji.
Hirono Hiro meets a girl named Miyamura Miyako on Christmas Eve while she's chasing a purse snatcher. Later discovering that Miyako goes to the same school as him they become friends. Unfortunately this leaves Hiro's childhood friend Shindou Kei feeling excluded. Kei begins competing with Miyako for Hiro's affection putting Hiro into a love triangle.
Asou Renji meets a girl named Shindou Chihiro at an abandoned train station. Hiro gradually learns more about Chihiro, including that she suffers from short term memory loss that causes her to forget anything more than 13 hours in the past. Chihiro has always dreamed of writing a novel but has been unable to do so due to her memory problems. Renji decides to help Chihiro fulfill her dreams.