The event is available after completion of class D preliminary round of ninja tournament. Additionally, there's one condition - you have to play with a different character than Naruto, Sakura, Kakashi, Yamato, or Sai. The event can be initiated on the beach, near the place in which you were dropped out of the boat when you came to the island. Approach two ninjas standing on the beach and begin the conversation. From it you will learn, that you will have to find their colleagues - Sakura and Sai.
You should start from Sakura - you can find her on the beach, to the West from where you've begun your ally event (point 1 on the above screenshot). Sai is located to the North from the place in which you've begun your ally event (point 2 on the above screenshot). Afterwards, you will have to get back to the beach, where you've spoken with the ninja duo. You will learn that there's one ninja remaining - Naruto. Go North from the place you've found Sai in (point 3 on the above screenshot) - you will find a boy there, who will ask you to find Naruto for him. He can be found near the place marked with point 4 on the above screenshot. After you've found the blond boy go back to the beach, speak with the group and win an easy fight with the ninjas.
After the encounter and a short conversation the event will be complete and you will be given the following rewards:
- 2000 ryo
- 2x Medium-thick substitution log
- Ninja World Tournament allies: Naruto Uzumaki, Sakura Haruno, Kakashi Hatake, Yamato, Sai.