She want that after school date with her 20 year old student
Thinking about it, this whole situation is just weird. It sounds illegal if you described it as a teacher wanting a date with her elementary student. But add the fact that her student is 20 years old aka her age, it just weird.
Could also be excused as 2 different narrators. One from the perspective of Roka and the other Chitose. Plus, her backstory was never really established or why she joined.
Plus you might be able to get feedback on your work or at least see a public's general opinion on their stuff. Because just playing/ showcasing your work in 1 place might just end up in an echo chamber where everyone likes it and you don't really grow.
Maybe they don't have the tech to do it without magic. Cause while they can have magic that can produce that pressure, the stone could block out the mana that might be embedded in the water to keep that pressure. Compared to the fire which could stay lit since it could be a fire starter spell...
Or he isn't used to bathing with other people completely naked. Plus, wasn't he enemies against Haruto earlier in the series so Raius could still be awkward about that also.