Nasu's sudden embrace of Ranko is just too much for the incredibly socially awkward girl. After all, she was only kind of starting to get into the mindset that they could maybe be friends...but romantic attraction from another male? Way too high a hurdle! Plus, the baby monster is always around and as possessive and clingy as ever, so it's hard to really consider Nasu's feelings when Kaya works so hard to makes sure he's first on Ranko's mind whenever, wherever...