Meihua Shisan earned her nickname—the Thirteenth Daughter—because she's literally the thirteenth daughter of the Plum Blossom Swordsman, a kung-fu master with a pretty specific view on gender: he didn't believe women could ever master the sword. Naturally, the universe gave him thirteen daughters instead of sons, which probably wasn't what he had in mind.
Thirteen got serious about swordplay after watching her father duel. Determined to prove herself and land a spot as his apprentice, she taught herself in secret. It worked out well enough that she's now ranked 38th among assassins.
As for her personal life, she caught the attention of someone called Seven after their second meeting, and he's been trying to hit on her ever since—something she apparently has to deal with regularly.
Content compiled by AnimeList.moe from publicly available sources.
