Mujin

After Konohagakure and Sunagakure decided to host a joint Chūnin Exams, Mujin and his teammates went to Konoha where the first exams would be held. Once entering the exams, Mujin and his teammates were randomly split into different rooms to take the written test. On a monitor, Shikamaru Nara explained that everyone only needs to answer one question on the test, but their team's combined score must equal exactly 100 points to pass. While everyone began to panic on how to pass the test, Sajin contacted Mujin and Mijin with his Sand Characters technique, telling them which question each should take.[1]

After the time was up, Shikamaru revealed as second question. He asked who the team would sacrifice in a situation that requires a decoy, noting that the answer has to be unanimous to pass. With his technique, Sajin told his team to choose Mijin. Later, Sajin and Mujin were shocked to find that many of the other passing ninja were still with their full team. Neji explained that the second question was a trick to test the team's loyalty; everyone was there because they chose no one. Another proctor — Temari, then explained that all teams without all three members were immediately disqualified.[2]