All in the Gang by thetroll

Chapter 1

Sango's lips thinned as Banktosu showed Kohaku how to handle a blade while her brother watched on careful eyes. She'd known prison would change him, but she never expected it to change him this much.

Even though Sango was a kendo instructor at the family dojo, Kohaku deferred to the tattooed man at their side—the one who had protected him in prison by taking Kohaku under his wing—for all his swordplay questions, nearly forgetting their purpose in coming to the sword shop to begin with:

The rumors of the jewel Bankotsu was hunting.

When Kohaku inevitably ran into a counter, Sango turned to apologize to the clerk. "I'm sorry, it's just that—"

She stopped short. It wasn't a clerk at all, but a woman about Sango's age with the bluest eyes she'd ever seen on a Japanese woman. 

"Don't worry about it." The woman smiled. "Totosai-san isn't the type to take offense, anyway. Right?"

The old swordsmith just grunted.