I just have the wild guess that Harold is the one involved with Penny.
He said he was involved with a common person. Then his mother appears near the magic tower.
Well, even if she marries Harold, she is already not getting her daughter as is, that's it (Butterfly Effect and yada, yada, yada)!
On another note, don't mess with Penny!!!
Well, he said in chapter 4 about her possible death...
Based on this page, the story should be in 2019. Namie Amuro retired in 2018, so if in the story one year passed after the retirement, then it should be 2019