The youngest brother after Shouka and Reishin, he acts as the proxy head of the Kou family. Because of his long rule, many outside of the clan believe him to be the true leader rather than Reishin.

A man of traditions and family loyalty, Kurou wields the enormous power of the Kou to protest the arrest of Reishin, single-handedly causing nearly half the country to cease functioning when he orders clan members to not go into work.

It is he who worked to get their father, the former family head, to pass over Shouka in favor of Reishin as the next clan leader, as he views Shouka as useless. In terms of personality, he and Reishin are more similar than he and Shouka.

Though he may view his eldest brother with disfavor, which does not prevent him from taking action on those who would act unfavorably against Shouka. When Kurou found out that the servants of Shouka's residence stole all the valuables, while Shouka remained in shock over his wife's passing, the proxy head ordered that each servant, to the last of them, be found and shown the tortures of Hell. Not only did that happen, their severed ears and eyes were sent to their families to warn them against any such future behavior towards a member of the Kou family.

Unbeknownst to Shūrei, Kurou comes to the capital in order to give her more protection than Shouka could offer that when she begins on the path of an imperial officer. To that end, he provides her the protection of the Kou clan via the travel pass made for her journey to the Sa Province to take up co-governorship.

Though the mark on the travel pass was of the Kou (Yellow) clan's, as it was Kijin who issued the pass, the special "seven-colored" ink used could only be made by the Kou (Crimson) clan, marking her as a person of importance to them.

He intends to have Shuurei and Kouyuu wed, with the two of them to lead the clan in the future.