Yup, Jun approaching Keima gave him quite the shock.
Supposedly, Keima should approach her slowly but surely, as the Gaming God states on how to capture teacher types. As Keima states, teacher types are the most tedious and time-consuming to capture. But IMO, these are actually the easiest ones to capture since all you have to do is to try 1) being her pet student by not slacking off in class or 2) to have her approach you if you're a problem student.
Keima falls under the 2nd category, which is something he didn't plan for. But hey, he's the Capturing God, so no woman is too difficult for him to capture.
Probably the main reason why teacher types are unpopular among VN tropes is the great amount of time needed to capture it, unlike the other tropes shown in KamiNomi so far which only require a different kind of strategy for each trope, but all of these can be accomplished in about the same amount of time for each one.
For example, a tsundere requires a different approach than a silent type, but both of them can be captured in 100 days or less, as several VNs require you to do so.
In fact, Keima did actually capture 6 different girls, all of them requiring different strategies for each one (athlete, tsundere, yandere idol, silent type, fighter, and average girl), in around the span of one school term. As expected of the Capturing God.
But a teacher? Man, it will take a whole school year at best to capture her!
But I think this is a very interesting arc. Keima will definitely capture Jun, and we will see his game plan in the next episodes.