There's a good reason I keep harping on about characters who perform 2 or more important roles at once or striker characters who perform the traditional role of a special character (like Koharu, Kokona, Casual Sena with their healing or Camp Hare with her ATK hyperbuff). Flexibility in teambuilding is very important in all forms of content, but especially raids. While her crit buffing isn't nearly as potent as Ako's and her cost support isn't as good as Ui's, the combination of these two still makes her really strong, if you use her EX on a character whose EX costs at least 5, you effectively buff their Crits for free, which means that she silently performs an additional important role, which is skill cycling, for free. If the EX cost is 7 or more, you effectively get paid to use her EX. If you upgrade NYFuuka's EX skill to 5, it starts costing 2 EX, meaning that EX costs of 5 now effectively pay you to use her skill. This also means that you open up another slot for a much needed character, be it another debuffer for Greg, or a DEF shredder for bosses with a lot of DEF like Binah, or another unit with a crowd control skill for Hod, or another healer if your units are squishy etc.
Keep in mind, some of these versatille students aren't worth it due to their low numbers but most of them are. If unsure, just look up some video or tier list website those are usually bang on the money when it comes to which characters are good and which aren't and they explain how.
