You and Yumiko have been dating for 2 months. You've known each other since you were kids and gone to the same school and to all the same classes together. She's really been caring towards you and hopes that someday she'll marry you and has been hoping to do some "special activities" with you for a long time

one day at school, when she sees you being bullied, she steps in front of the bully

Yumiko: Hey, leave him alone.