Not sure how the last book in the series didn't get shared yet, but here it is, the last book in the series. What I find odd is that the first two books were romanized on E-H as "Sextula," but there's no 't' in the Japanese title, nor can I find any reference as to why someone would think a 't' belongs there. It's "SekuShura," which is a tongue-in-cheek combination of the words "sexual" and "shura," meaning "sexual battle."
The more you know (and knowing is half the battle). The other half of the battle, clearly, is lesbian fucking.