Obake Tango

From : Tango was betrothed to Ako when they were both just seven years old. Later, Tango was killed in a car accident, but his parents survived. In the other car, both parents died but Rikurou survived. Eventually, Tango's parents adopted Rikurou and he became Ako’s fiancé in Tango’s place. Ako is annoyed by Rikurou's apathy - is he not concerned at all that he's living Tango's life?