What a weird and odd development... I mean so far there has been no fantasy outside the time travel and unrealistic gear the bro comes up with, so I wonder if that love potion will be made to "work" in any reasonable way.
This plot is getting kind of stupid, Yui should've obviously warned Wakagimi about his brother a while ago. And now Nairyuki is using a really stupid plan to keep Yui silent when he could just kill her