- The Tuning Fork was created to control Ikuto's actions and increase the stages of brainwash if Ikuto was to ever try to break free or attempt to escape.
- It can be used with or without the technology that help it send signal waves to Ikuto's violin.
The Tuning Fork seem to give Ikuto side-effects whenever its in use or not. As it clearly shown that Ikuto gets exhausted when it is not in use.
The Tuning Fork could be responsible for Ikuto not having any memory of being Death Rebel. But this is unknown as there is no explaination in the anime/manga.