Is it just me, or did this chapter seem kinda...I dunno, random?
Maybe, but you still can follow the line of how it went.
we already knew that Uki was the little sister of her big bro (I don't remember his name) and that they went to the same class, so there was the doubt of how she hid her kappa characteristics if her twin brother didn't, so the mangaka started with a focus on the brother and quickly answered the question, it added a bit of world building with the water spear part, made some foreshadowing with the sisters part,and ended showing how mizudako used her powers by accident because she wanted male lead's attention