I honestly adore this story in it's own way. I kind of wish the story was just about the Teacher, Mother and the Rival when they were young and get rid of the Time-Traveling son as they don't really go together. If it was just about the Teacher, Mother and Rival when they were young then I think this would be a really interesting story and fun story cause the Son can really take me out of the happy mood. But the Son is surprisingly not a bad character.
I honestly see it like this. The Mother due to her sons interference ends up dating the Teacher/Delinquent/Yankee girl and Hanada and the Son/MC start dating. Honestly though. Hanada may just be the best girl and I do feel bad for her sometimes.