Hrmmm. I just tested this feature in newest version and it looks like they finished implementing the time travel. Books 1 and 3 are fully explorable. Book 2 you have to do a little talking around with Azula before you get the option to leave. If she says she wants to blow you, argue with her and pick sex and cum inside. You get an impregnation animation that plays and I think that's what triggered the option for me to leave again.
What kind of logic is that? It gives you the damn option. So, if don't use a youth potion, the bodies shouldn't be youthful. Yet, they are. That's what I'm saying here...
The cutscene is in the Airtemple Island location, at the very end of the game (just before the introduction to the epilogue). Meet Ikki in the pavilion
i have only the option for the naga or the spiritThe cutscene is in the Airtemple Island location, at the very end of the game (just before the introduction to the epilogue). Meet Ikki in the pavilion
You need to have choses the "right" options in order to open up Ikki's additional dialog options, starting all the way back in the first area during the snow storm. The answers are mostly obvious, but if you need specific instruction, using the search function in this thread with the keywords Ikki & choice/choices will probably get you some useful results.
As kDarcsen wrote, you must first show interest in this type of "activity"
There are a few optional dialogues that you should have a certain way, just go back to the save from before the blizzard that you wait with Korra in the cave and read the dialogues carefully 
to perv down on little girls, the most obvious would be the most perv choice, if there is. so, you tell the girl that you like small boobs, or the likes, you be ambiguous instead of saying No, and so on. MiTy have done a decent job giving everyone who wants to avoid that erm, 'darker' path, a stack of exit choices. funny enough, i bet noone of the accursed patreon staff did ever play any of what they host.
