> The author probably realized that harem route isn't gonna work for this manga so he cut it clean.
Considering his past, I suspect Hata-sensei was trolling us from the start with the mere thought of a harem angle. But I will concede that I didn't think he'd kill it quite so soon. I'm glad he did though as this should be a Tsukasa x Nasa love story with fun stuff all around. That is, until the "death flag" Hata-sensei has been teasing us with is set. ?