Mai is a thief and former Adachi servant, and the last of the conspirators you hunt in Masako's Tales. She and Masako were secret lovers before she was sent away for stealing. She looted the Adachi estate after the massacre.
She tells the Straw Hats a story about a girl who takes revenge on a monk, a thin cover for her own. Jin and Masako take out the ronin quietly, and Masako talks with Mai alone. Mai never knew who led the plot, but says the leader wanted to start a clan.
Masako spares her after she leads them to the heirlooms and lets her keep the comb. Mai goes home.
Junshin
Junshin is a kind monk who turns the Golden Temple into a refuge and runs survivor camps across Ariake. He is the man Jin and Masako keep going to for leads in Masako's Tales, though he worries about her thirst for revenge.
Masako Adachi
Lady Masako Adachi is the only survivor of Clan Adachi and one of Jin's allies. Her husband and sons die in the Mongol landing and the rest of her family is murdered the same night. Her side storyline, Masako's Tales, has you hunting the people behind that massacre.