おこちゃま戦争 (Okochama Sensou)

Background
There is no other battle fought more honorably. Yai Yai Yai Yai~tsu!(`o´) "Kiddie War" is an original song by Giga-P and is one of his most notable songs. It was uploaded to YouTube on October 6, 2014. This song tells the story of two siblings (Len and Rin) 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 upper hand 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, Len and Rin's version was released at the same time. It's one of the Kagamines' most notable duet songs.

This song has entered the Hall of Legend. It is featured in the album Download feat.初音ミク.