Hakumei Ni Michiru summary:

The youngest son of the Shin family, Shinhou, has idolized Shousei, his childhood friend and mentor, since he was young. He vows to become the strongest in the Shin family and win against Shousei, the strong, beautiful, and dignified figure he admires and trusts.However, their families’ conflict forces them to turn their blades against each other… Shinhou, under orders to exterminate the entire Shou family, refuses to fight Shousei—the person he loves and cherishes most—and allows him, the sole survivor, to escape. In doing so, he chooses to part ways from the path they once walked together, knowing they will never meet again.Fifty years after their separation, Shinhou returns to his family home following his father’s assassination—only to find Shousei, whom he thought he’d never see again.