"I Won't Forget the Magical Girl") is a Japanese light novel by Yasuyuki Shinana [ja] and illustrated by Hagu Koshijima [ja].

Half a year ago, high school student Yūya was introduced to Mirai, his younger sister.

[5] A live-action film adaptation was released on April 23, 2011, starring D-Boys member Ryuki Takahashi, Risa Taniuchi [ja], Idoling!!!

[6] The film's theme song is "Kimi ga Ita Shirushi" by Jurian Beat Crisis.

[3] For the live-action adaptation, Real Live reviewed the film favorably, commenting how the director, Teiichi Hori, is able to "replicate" the "sweet and sour youth" from light novels.