Responses
It doesn't explicitly say he did it on purpose. He was drunk and it was Winter and it gets pretty cold in Japan especially if you're not covered properly. So it very well could have been an accident. But also he could have just wanted to die after what he tried to do to his friend. We'll never know. I'm, however, choosing to believe it was an accident. :')
OMG why of all the death in the world he had to freeze to death ┗( T﹏T )┛ isn't that just suicide?