Kiyotaka explains to Suzune what he did last three days before test. And why everybody get such good scores on tests. But Sudo failed tests anyway and is going to be expelled.

Even during summer vacation, lone wolf Horikita would rather remain locked in her room studying than interacting with others. One day, Ayanokouji invites her to visit the pool with some of the others.

As part of a special test, the school has brought the students to an uninhabited tropical island where they must now live for a week. Their performance on the test can have an enormous impact on the point standings of the four classes.

Class D has achieved a degree of unity in facing the special test, so Ayanokouji and Horikita head out to see how the other classes are getting along. Class B is working together to make a comfortable life for themselves, while Class A remains secretive.

With the panty thief incident already eroding Class D's trust, Horikita finds her leader key card stolen. While they try to figure out who did it, the base camp is thrown into chaos with a new incident of arson.

Survival test is coming to the end. Things don't look well for 1-D. Key card is stolen. And now Suzune is forced to withdraw due to her sickness. Kiyotaka will try to turn things around.