Yeah, i wondering who this tall woman who look like Shy and was the previous Japan Hero. God, that is probably the least subtle implication i've seen in some time. Also 73 chapters to know that there was a precedent Japan Hero and know that raise some questions. How did they change Hero in countries ? How they're even choose ? Was Shy ignorant of who was the previous Japan Hero ? If it's really her mom (which is very possible given the hint), since when Japan don't have an Hero ?
At this point, I'm not ruling out that this was a time traveling Shy.