As we know, Sonic and Flashy are close friends. Both are the last remaining members of a ninja clan. They rely on each other to maintain their territory during the rigorous training process of their village. However, on the day of graduation from Key 44, Sonic was unexpectedly injured, causing everyone to be shocked, and he fell unconscious in his room.
So why did Flashy let Sonic get injured?
1. The incident of Sonic getting injured occurred during Flashy’s assassination mission

In Flashy’s story, he mentions that he had assassinated a teacher, students from the ninja village, and other graduates on graduation day. After doing so, Flashy immediately left and began a new life as a hero, stepping into his high-level ninja abilities.
Interestingly, on the day before yesterday, Sonic was unable to attend the graduation ceremony because he was injured. This was when people discovered that Sonic had been injured.
2. Flashy believes that Sonic could survive even when exposed to the toxic substances he created
To injure Sonic, Flashy had been using a common method involving toxic substances in food that he usually eats. Flashy himself strongly believed that this level of toxicity would make Sonic feel as if he was about to die, but in reality, he could still survive.
Flashy also understood that Sonic had grown up in a harsh environment for a long time, so his resistance level couldn’t be underestimated. This fact was proven when Sonic survived after a deadly attack caused by a monster that had taken a direct hit.
3. Blast suspects that Flashy merely wanted to keep Sonic away from the assassination mission
After hearing Flashy’s story, Blast began to suspect that this ninja hero did not genuinely want to harm him. He realized that the real reason behind Flashy’s actions in injuring Sonic was to prevent him from attending the graduation ceremony and to keep him safe from the ongoing assassination event.
The reason relates to Sonic’s potential to change the structure of the ninja village. He wants to create a new ninja village based on his desires and allow those who are left behind to live according to their own wishes.