She wasn’t sure why she hadn’t thought of it before. While an actual euphonium wasn’t at her disposal, there was the next best thing: guide books! (Or sheet music, but there was no shortage of that at her place of work.) “Music theory,” Natsuki mumbled offhandedly, wandering further into the aisle and frowning up at the looming shelves. Just how did this store’s organization work?  “Ah... Excuse me.” There was a boy in the way.