Ep. 13: Riki discovers Mio's shadowless doppelganger Midori and faces memory loss regarding their beach encounter.

13

Riki encounters a girl resembling Mio in the courtyard, but she vanishes quickly. Mio stays absent from school for days while others gradually forget her existence. Riki later finds Mio, who gives him a poetry book and invites him to the beach. At the beach, Midori appears and reveals Mio lacks a shadow, which explains her parasol use. Riki suffers narcolepsy and wakes up in his dorm with no memory of the event. Normalcy resumes until Riki finds the book and seeks Mio in class. Midori enters, and everyone else identifies her as Mio. Riki refuses to accept this, noting Midori also has no shadow, leading him to suspect she is Mio's shadow. Midori warns that Riki will eventually forget Mio too.