The young Yamato Yousuke searches for a way to follow in the steps of his father, a detective who passed away in mission trying to save a little kid who got kidnapped. Finally, an opportunity to become a detective himself has arisen, but in the middle of carrying out his first assignment, a test to see if he would be a good detective, Yousuke suddenly gets hired, apparently for no reason. There must be a secret behind all this...
(Source: aarinfantasy)

From Blissful Sin:

Yasukado and Yasutoki are twin brothers born as the heir and protector of their family's feudal household. When an assassination attempt is made on Yasukado, Yasutoki must do all he can to protect his beloved brother and lord.