The author needs to work on the sister's apparels. Like draw her in a more fashionable clothes. That's my personal preference tho. Nice chapter like always btw. But why kubo looks sad in last page tho
I'm going to say that the principle of Chekhov's gun will be at play here which means that "aqua" would show up in future chapters, in some form or another
Also that electric spark when Kubo and Shiraishi saw each other reminded me of 100 GF