Board Thread:Manga Discussion/@comment-25819382-20170718215047/@comment-31525652-20170719001837

She's a woman.

In chapter 350, it has been revealed that Halkenburg didn't get along with his mother and two sisters.

Duazul (their mother) had 4 children --> Camilla, Tubeppa, Luzurus and Halkenburg.

It's pretty obvious Halkenburg and Luzurus are men, so that basically confirms Tubeppa is the second sister.