Yoruhiko is the younger twin brother of his sister, Akane. When Akane gets into an accident and goes into a coma, Yoruhiko pledges to maintain her perfect attendance by impersonating her and attending Akane's school. Very quickly troubles come up regarding how long he can continue pretending to be her and he feels guilt right off the bat. However, his appreciation for his sister keeps him going as he does not wish to let Akane down.