This specific arc has been on my mind for a few days and I just can't remember which novel it's from despite checking through my worldhopping tags ): It was an interstellar? arc where the mc had been a student who had been studying music and wanted the world to hear his voice. The ML was undercover I think? honestly might be mixing up some stuff but the main idea should be right. The ML was forced to torture the mc and had to like plug this electric shocker or something into his head which most people weren't able to endure. It was like some extreme torture stuff that was later revealed in a video so that it could clear mc's name. The mc ended up singing their national anthem or something like that while detained and there were also others detained with him who had initially given up until they saw the mc enduring. ML felt really bad when he exposed the video of the torture since he remembered what he had done and regretted it. I think the mc ended up with his vocal chords ruined at the end and was unable to speak where he lived out his life with the ML until heading to the next world. Thanks for any help ^^
Could it be "Pleasing Start Over" ? I have yet to read it but the third arc is an interstellar music arc. If it's not this then I'm not too sure as I don't think I've read an interstellar music arc before