I don't know if Siren have already plan for scene with Leslie but personally I hope for a proper sex party event. I was surprised despite the fact that the MC has theoretically 2 harems (one at home and the other on campus) and the ladies know everything and are happy with it there was no proper sex party/orgy, there is a pool event but still I hope for something "bigger". Such an event would be relatively easy to create, all ladies in house have naked models, they just have to be brought to one place, make a sprite scene with 5/6 of them and a sex scene with Leslie. That will be a proper end game event/reward.