Ryōku hates the Star clan with all his might, that was uttered exclusives distain comes from his unnamed parents being killed by the Hoshizoku, a line the Japanese dub. While his entire village hates anything to do with the assassins, Ryōku at least finds some solence in the fact the clan does not exist anymore and as stated by Black☆Star.
Black☆Star and Ryōku fought after Ryōku was possessed by the demon blade, Black☆Star freed him from the Kishin eggs control. After the battles are over, Ryōku says even if Black☆Star wasn't Star clan he still would not like him with a smile on his face.
Masamune NakatsukasaUnder Masamune, the demon blade's influence, Ryōku fought against the two assassins, Black☆Star and Tsubaki. Masamune performed the Soul Possession on Ryōku which he used his body to fight against the two mentioned above. Masamune found the fear of Black☆Star inside Ryōku's heart and was easily able to manipulate him from inside his soul.
Using his power, possessed Ryōku bested Black☆Star and Tsubaki, utilzing Masamune's shadow powers. After everything is said and done, Ryōku apparently wakes upon having no memeory of the events and a new found "respect" for Black☆Star.