this is my first time asking here so please let me know if something's out of formatting. I'm transcribing this short piece called Vampurity by Shinji Iwai (it's a soundtrack to one of his movies) as a mean to:

1. learn how to transcribe
2. analyse and try to comprehend the piece.

Here's the first 5 bars of the transcription I made:

My question can be subdivided in two:

1. is the key B minor or is it D major?
2. irregardless of the key, why and how does the C major triad work there if C is not in the key?

Thanks guys!

I'm transcribing this short piece called Vampurity by Shinji Iwai (it's a soundtrack to one of his movies) as a mean to:

1. learn how to transcribe
2. analyse and try to comprehend the piece.

Here's the first 5 bars of the transcription I made:

My question can be subdivided in two:

1. Is the key B minor or is it D major?
2. Regardless of the key, why and how does the C major triad work there if C is not in the key?