Class D is no longer Class "D". They are now in Class "C". All the students in the school have to attend the school event that takes place in the mountain. But it's not the kind of desert island. They cook breakfast themselves, wake up before the due time, cleaning, take lectures and then pass exams of Zazen, Running, Speech, usual paper test on the final day. Boys and girls are separated during the event. But they can meet at meal times.
Each grade has to make some groups and those groups have to be made up of people from two classes at least. (Small group). Then those groups join in groups that from other grades (Large group). The results of the test score are averaged, and it makes a ranking. Ayanokouji's group has Ishizaki and Albert from Class D, Kouenji and Yukimura from Class C, Sumida, Moriyama, Tokitou from Class B, and Yahiko and Hashimoto from Class A. (10 in total). Yukimura is the leader. From grade 2 and 3, Nagumo's group join in them. During the forming groups, Nagumo suggests a battle to the former student council leader, Manabu Horikita, and he accepts it, which group gets higher score. They set a rule to let it be fair and square that they can't take dirty plans like attacking their group members.
A sudden d*ck competition is brought up at the bath time. Ayanokouji, Kouenji (Class C) > Albert (Class D) > Katsuragi (Class A), Sudou (Class C) > Kaneda (Class D) Albert "Oh my God". Ryuuen has an atmosphere telling his is actually big and actually tells it can't beat Kouenji, but the comparison doesn't happen since he just attracts guys' attention to himself to let them notice that there is Ayanokouji hiding his. Kouenji is sure that he wins in terms of "experience".
Nothing imporatant happens between Suzune Horikita and Kikyou Kushida in the volume. Horikita fails to convince Kushida that she will keep the secret.
Sakayanagi takes a certain plan to beat Ichinose, and it actually works so that Ichinose can't even show smile to her close friends when they talk to her. The plan isn't revealed in the volume.
When Kouenji gets out of the path to fight against a boar, Ayanokouji runs after him. Then the moment Ayanokouji holing Kouenji's arm, Kouenji realizes who is the person behind the Ryuuen's sudden retirement from the leader. Apparently, Kouenji won't reveal it. The boar thing finishes sooner than Kouenji expected, just in case you wonder.
Nazuna Asahina, the 2nd grader, is nice and known for her nature that returns the favor and never forgets it despite her way of talking and appearance. She lost "Omamori" charm/amulet, but Ayanokouji picked it up so that it's returned to her. That's why Ayanokouji can get the chance to talk to her, and they can talk about Nagumo in this volume. She is not one of the sympathizers for Nagumo. But she says he doesn't take dirty actions and keeps his words. And regarding the topic about the girls' group in the school event, Ayanokouji tells something to her to end the conversation. It's not revealed in the volume.
The results of the test is Manabu Horikita's win. But Nagumo's dirty plan takes place in the girls side. A group's average score is lower than the score the school sets, then the leader (Class B in Grade 3) gets the penalty to quit school, then she names Akane Hori as the one who caused the trouble and quits school. But her class and Manabu Horikita use points to revoke that. Class B also does the same thing.
The volume ends with a line for the future reference that there will be dropouts one after another from now on.
Ayanokouji tells Kei Karuizawa that he will protect her from dropping out whatever it takes.