A project to commemorate the 10th Anniversary of Tsukiuta. 

The Black Rabbit Kingdom and the White Rabbit Kingdom — Two different worlds existing side by side. The two worlds, which were supposed to be a "pair," had never met, perhaps by a twist of fate. The situation remained unstable and incomplete.
 
Hajime, the young king of the Balck Rabbit Kingdom, is distressed by the calamities in the surrounding countries. The Prime Minister Haru, his close aides Kakeru and Koi, the prince Aoi, and his escort Arata are busy preparing for the upcoming World Congress and the ball to commemorate the 15th anniversary of Hajime's reign.
 
At the same time, in the White Rabbit Kingdom at the suggestion of Shuno, who calls himself the Demon King, the king, Kai, the prince, Rui, the guards, Yoh and Iku, and the former military officer, Yoru, are going on a "picnic" to the Black Rabbit Kingdom.
 
What will be born from the encounter between the Black Rabbit Kingdom and the White Rabbit Kingdom? 
(Source: Crunchyroll News)