Isaku is frustrated with Keiya when he doesn't even try to pass his tests at school. They agree that she'll give him a reward if he passes his next make-up exam, but the reward he asks for is nothing Isaku could have expected.
Dummy...
...غبي
Dummkopf.
Tonto…
Bobo.
Imbécile.
Scemo...
Bobo...
Болван.