Koukyuu ni Hoshi wa Yadoru: Kinkakoku Shunjuu

Following the death of the emperor, the prestigious Hoshi family of the Golden Blossom Empire has decided that all members must commit suicide. Yuukei, the frail heir of the Hoshi family, is also among those targeted, but he narrowly escapes. But now he is being pursued...? (Source: Kadokawa, translated)