Abe lied to the world about Fukushima, and a lot of American and Japanese military went into the radioactive hell hole and were exposed. Lots of these people now have Leukemia and rare cancers. My theory is that this guy had Leukemaia and was going to die soon. He blamed Abe for it.
The guy who killed him was reportedly once in Navy.
He was in the Maritime Self Defense Force 2003 to 2005.
Fukushima happened in 2011, after he was out.