The last Swordmaster's heir (BL)

Niris, an angel in his twenties, goes to the ceremony of the year in Yerpena, the capital of the demons. Prince Seiran is to become crown prince, and the whole intergalactic aristocracy will be at the reception! But the angel is not really coming for the same reason as everyone else... he has a secret mission that he must accomplish during the ceremony and on which the lives of many angels depend. Will he succeed in lifting the veil on the traffic he seeks to uncover?