>>536358590
Yeah you use rio to effectively get 2 shiroko EX's in each buff window, just re-cast it when she starts reloading. Serina lets you both rotate skills faster and lets you spam without worrying she'll run out of HP.

>>536358672
My buffs kinda suck (EX2 and EX3) so I need to cast her shiroko's EX more frequently than she has HP. I did do it once in practice but it's super tight, I only was able to pull it off when Tsubaki died in p1 which got ako to heal her giving me more EX uses.