That Man, for the Sake of the Kuchiki

Plot:

Centuries ago, Ginrei Kuchiki, Byakuya Kuchiki's grandfather, and his son-in-law Koga Kuchiki were assigned to bring down the rebel forces threatening the Seireitei. With his Zanpakuto Muramasa's power, Koga wipes out the renegade Soul Reapers one after another, and soon his strength becomes known throughout the Soul Society. Yet Koga himself was frustrated by the fact that his father-in-law Ginrei did not seem to acknowledge his accomplishments.