Our Last Crusade or the Rise of a New World, Vol. 4 (light novel‪)‬

A SECRET NEVER TO BE TOLD...
To rest and recuperate from their set of life-threatening missions, Unit 907 is finally granted a much-needed break. And what better place to spend time off than at a distant resort where they can lounge in their bathing suits 24-7? Against all odds, the trip is going according to plan...until Iska bumps into a certain witch who instantly reminds him of Alice. In fact, it feels all too familiar when she demands he come to Nebulis-for reasons she simply cannot reveal. And she isn't the only one with a hidden motive: Alice has arrived to investigate why her sister has been spying on Iska...for months.