Ai will most likely be sharing a space somewhere with Yuuki and Zero (or more, idk). Not sure where but eh, well. She will be taking advantage of all of the activities that are available even though it means sunlight. Which she will have some sort of jewelry to help her deal with even though it doesn't actually hurt her.
Soushi will wake up and be physically the same but he will definitely be more outgoing because he is social, he's just awkward about it. He will probably be living in a water hut with Kazuki for the period of this event but may not even be spending a whole lot of time there. This is just the sort of thing he needed to get out of the library and out doing things. He'll be interested in visiting the museum to see all the different things about different worlds, going on the ferris wheel, watching the fireworks, hanging out on the beach even if he doesn't necessarily go swimming all that much.
He will definitely be taking a boat trip, going to the theater, and Kazuki will probably get him to go exploring of all the natural wonders so that is a thing.
Basically, Soushi will be around doing things other than sitting around reading (though he may have a romance novel when out at the beach).