Kaiju No. 8 Vol 1

Kaiju No. 8 by Naoya Matsumoto. An Action manga rated Teen, published in English by Viz Media.

Kafka Hibino always dreamed of joining Japan's Defense Force to fight the giant monsters that attack the country, but at 32 he's stuck cleaning up their remains. Just as he gets a second shot at his dream, a mysterious creature turns him into a kaiju himself.