Really o.o? I thought the emotions were being expressed quite well when he sang in the anime. I felt like I could feel the anguish and sadness. I feel like he wouldn't be able to express it unless the song was rock. Heck I even had the song in repeat XD and went back to the part in the manga where the song begins, it overlaps pretty well. just needs to be a bit more louder is what I thought or faster.
Oh? I felt his emotions. I felt it so badly that I watched it with teary eyes!! It was... so sad. He was sad, even his voice was cracking (I heard it at the beginning of the song). In my opinion this song came out way better in rock version than if it would be in some softer kind of music. Even Mafuyu said (to himself) he can't cry and it hurts so bad that he want to scream. I was hoping while watching that this type, this genre of music eventually could help him to express his pain. Maybe in some part: to get free from this hell, even for a moment.
I think the rock version was the smartest move the producers could’ve done. I actually don’t think this scene would have worked well with a sad and slow tempo song. The anime’s rock version fits extremely well. He’s not there to sing a love song or a song of regrets and sorrow. He’s there to MOVE ON.
The screaming quality and the fast pace of the song made it seem even MORE raw and tear-jerking. The emotions shot through the roof for me. This song can’t be pretty. It can’t be soft and mellow. It can’t be emotionally sad. It has to be about breaking free and screaming all the words he never could out of him to move on. I personally thought the anime song was a hundred times better than whatever they originally had on the drama CD. I cried a bucket listening to it.
I’m sorry it wasn’t the same for you.

Am I the only one who expected Mafuyu's song in the anime episode 9 to be more emotional? Somehow that moment when he sings was better portrayed in the manga than in the anime. Even though there was no music in the manga, you could "see" the emotions.
I mean, in the anime, the lyrics are touching and bittersweet, but the emotion in the singing, I feel that it was off, or then the song was too much of a rock song that it was difficult to sing "emotionally".
But I especially liked the instrumental version of Mafuyu's humming that played near the end of the episode during the beach scene with Yuuki. I feel like if they would have made a "softer" song like that, it might have been more expressive, or "easier to relate to". But sadly, somehow, after watching the anime and hearing Mafuyu's singing... the manga doesn't feel as intense and emotional anymore, because the anime's songs are ingrained into my mind. But this is just my opinion. If you could relate to Mafuyu's singing in the anime, good for you. I unfortunately couldn't ╥﹏╥