Kang Han-moo

Kang is the teacher of the summer school, wanting to help the children with their problems making school difficult for them. Most of his approach to this is organizing many physical outside activities to keep them busy, exercising and active. While a bit strict, he is good-hearted, but is shown to have a weakness for pretty women. This is shown when meeting Yobi's Mother (actually Yobi in disguise) he seems to be instantly attracted to her and makes up excuses just to have her revisit the school.

(Source: Alchetron)