I really have very little to go on with this piece. I've never heard it until as I'm writing this, and I've never heard of this composer, either. I got nothin', folks!
Masao Ohki was a Japanese composer who lived from 1901 to 1971. Here's the most extensive biographical entry I could find.
The work in question is Ohki's Symphony No. 5, subtitled Hiroshima. It's a very modernistic work, often atonal and impressionistic. There is little light or optimism to be found in it, as might be expected from a work so titled. I honestly don't have a great deal to say about it, other than to note that is an undeniably powerful work.
Tomorrow: An opera hit!