Based on a hentai video game, Mizuiro tells the story of two girls who have strong feelings for Kenji. The first episode focuses on Yuki, Kenji's younger sister, whose obsession with her brother causes her sadness. This is particularly poignant given their sibling relationship, even though Yuki was adopted by Kenji's father. The second episode follows the clumsy Hiyori, who emerges naked and ghost-like from Kenji's dresser. She tries to convince Kenji to fall in love with her, despite having no memory of why she appears from the dresser.