If you think about each chapter being ~8 pages, it doesn't really feel like it's dragging that much? The author is letting the story breathe and develop on its own, and that means letting arcs for all the characters, including Nisaka's, run its course.
On a side note, I really enjoy how well this shounen ai storyline is being integrated into this shounen manga. The genres of BL/GL and shounen/shoujo are so separate that it never seems to overlap. If anyone has any recommendations of other mangas where this happens, I'd love to know!