第几滴血？

This achievement only requires you to beat every stage with a perfect kill value. It does not take score into account, you do not need to get SS ranks and getting hit by projectiles is fine.

This achievement has no cultural references in the English and Chinese versions. It is likely specific to the game. Following the trend some Hanu Wars achievements are following, the title could reference how the player, playing as Hanu, has lost track of the drops of blood they spilled from killing enemies and completing challenges flawlessly in the mini game.