おこちゃま戦争 (Okochama Sensou)

Background
Yai Yai Yai Yai~tsu！(`o´)

The song tells the story of two siblings who, at the request of a butler, aim to best the other for the throne.. The two engage in a "Childish War", both of them trying to gain the upperhand over each other in order to prove to the butler that they are the one worthy of the title emperor. However, all of their squabbling results in their contest ending with a draw.

The song was originally written by Giga-P and Reol for Kradness and Reol; however, Rin and Len's version was released on the same day.