宿題の絵が描けない優は、みどりからある森へいけば上手に描けると教えられる。幸福の森と呼ばれるその場所は、13歳で行方不明になった天才少女画家、中原美也が最後に訪れた地だった。優は森から異世界へ迷いこみ美也と会う。一緒に帰ろうという優だが、突如現れたユニコーンがそれを邪魔する。
Posi and Nega scolding a frustrated Yuu for procrastinating on an art assignment she was charged sets the stage to have explained her a forest fabled to enable anybody to draw with a great deal of skill; desperate to avoid the turbulence for not doing her homework but also curious, Yuu decides to set course for the forest where Midori explains Miya Nakahara who prosecuted a prolific year-long art career a decade ago at only 13 years old before disappearing. Upon having it explained that Miya will catalyze sincere efforts to develop the artistic skills of those that draw in the forest, Yuu races off into the forest to try her fortunes only to find that success can have far more dire consequences than failure when she encounters the Unicorn Deshi who leads her into a face-to-face encounter with Miya in a pseudo-reality that she cannot easily leave on her own when the Unicorn Meijin takes her prisoner with the exhortation to reside in its world with Miya. Even though Miya yields to her co
