When the spoiled and rich Serena look-a-like, Reina, transfers to Keidai's school and Yuuma's grade, her constant attention to Keidai sparks the competitive and protective spirit in Yuuma. But as the "twins" vie for Keidai's attention, Mii feels slightly left out, torn between her feelings for Keidai and her "duty" as his best friend to encourage him to be with "Serena."