Big plot hole or story inconsistency.
MC and May are supposed to have no memories of each other, how then, does MC remember May wanting to go to a prom before the end of the world? And it's at the start of the event it's made clear they're only getting on until the memories are restored, so how does MC remember anything? Why did May ask if he remembers? 
And when are we supposed to have been shown Mays powers? The first we hear about them is when they're talking about how she feels weird using them. It's implied they're nuclear powers of some sort, but that's our first time learning anything about them and it's treated like we already know her powers
Just noticed that my reply was never posted... Here it is then
You're right about the plot hole here. I'll fix that in next version. I haven't paid enough attention here, my bad.
About May's power, you don't get too see exactly how they work but as you said, it's implied at the end of Chapter 1 (especially on the last pic).
