Disappearance of the blackboard erasers
Season 2, Episode 100
Kodocha 100
Air date March 13, 1998
Episode guide
Come check out the good karate club
The trio disappeared together

Nakao, after having fallen passed out on the floor, is taken to a hospital, but immediately gets up, despite still feeling very unwell. He forces himself to go to school, but soon collapses again. He is taken back home by his mother, and he realizes that this is the first day that he's ever missed school. This is fairly devastating to him, as he was quite excited to continue karate club, and was sorry that he missed Sengoku's class, whom he respects greatly. The next day he goes, and first meets up with Akito to apologize for missing the last day. However, he suddenly says that he should quit, as he's not cut out for it. Nakao is devastated once again, karate club being the one thing he looked forward to.

As he's walking down the halls, he meets Sengoku, and he apologizes for missing his class. Sengoku, however, didn't even realize he was in his class, as he never has noticed him. Now Nakao is truly hurt; Sengoku and Akito, the two people whom he looked up to most, had both treated him as though he didn't matter. After school that day, he goes to the karate club anyway, but stops before he gets there, listening. Sana is talking about recruitment, but doesn't even realize Nakao has gone. They all forget his name, and while they are disappointed that he's gone, don't see it as a major loss. Nakao walks away and goes home, where he is once again disrespected by his brothers for not making the dinner they want. He drops cooking dinner altogether, laying down in bed, and contemplating his purpose. The next day, he's gone, and his mother just assumes he's already at school. However, he's actually sitting in the closet of the abandoned north wing of the school, and having taken the erasers throughout the school with him, the school notices the change without him, but not that he's gone.

Sana begins her unorthodox recruitment techniques by dressing up in a bunny suit, as opposed to a sexual playboy bunny suit as Ishida had expected. They attract no one else, but Sana keeps on moving, if not just for Akito, but because the whole ordeal has been a fun process for her. Meanwhile, Nakao's mother notices that he's still gone from home, and becomes worried. The next day, they contact the school, who begins to investigate. A meeting between Nakao's parents, Principal Ari, Head Teacher Kyoutou, and Sengoku leads to them picking up the lead that he'd joined karate club before disappearing. Sengoku immediately assumes that this is why he's gone, and sets out to blame Akito. Suzuki says he's being paranoid, but Sengoku insists that Akito must be purged, for having been bad the year before.

Sengoku knows his evidence is weak, but suddenly picks up a letter that changes everything. Nakao left a letter talking about how the reason he'd joined karate club being that Akito approached him, but that he worked himself too hard nonetheless. Sengoku assumes this is the perfect case against Akito, but suddenly reads the second page, and decides to hide that part. He brings the first page of the letter to the office with Principal Ari and the rest, condemning Akito and Sana, who'd been saying that Nakao had shown no sign of being pushed too hard, just that he was weak, quiet, and somewhat effeminate. Sengoku reads the letter, and the one most shocked by it is Akito; he had no idea that he cared about him so much, or that he had actually wanted to stay in the club when he kicked him out. Sengoku grabs him by the neck, demanding that he apologize to the family and take full responsibility. He finds himself unable to speak, but Sana grabs Sengoku's arm back, telling him that it's more important to find Nakao. Principal Ari agrees, and sets everyone to a task to help find him. He then asks to speak to Sengoku alone.