manga going at 100 mph. this series better not turn into a 200 chapter thing because I seriously don't think the author has what it takes to keep inventing scenarios to advance the plot
So he's at least 7 years older than her. Assuming she was in 5th grade when he was a college freshman.
That's the best case scenario though. He could've watched that anime as a college senior while she watched it in 1st grade, which would make him around 12 years older.