"What would (Reika) do then?"
The stupidest thing possible in every scenario ever. I think you or your wife may have dropped her on her head a few dozen times as a kid. Intelligent girls don't hang out with a bunch of guys they barely know when they have a supposed stalker.
When we next catch up with her we better find out that she screamed, yelled, shouted, kicked, and fought since they were in public around a bunch of other people. This may be Japan but people are still people, cause enough of a scene and people (even authorities) will get involved.
If she just ran and stayed silent the whole time she will join the Manga hall of fame for stupidity.