Context is that Sui was explaining to Aqua on why "bless you" became an expression to say to people who sneezed. It's because the belief that the devil would snatch your soul if you sneeze.

Towa came back after grabbing something to drink and only heard the end part of the convo, "Oi Towa, stop stealing their souls!" and clueless as she is, could only reply with a blank "Yes" lol.