Literature
Shinigami Realm - First Human's Insight
Shinigami Realm - Dead Land, and the First Human to Travel There
The term 'spirit world' does not represent any single place, or location that is physically inaccessible to humans. The term represents any realm described in any belief system that humans have either invented or developed after witnessing a supernatural event (such as plagues of Egypt, or life, death, and rise of Christ).
Until 2003, the Shinigami realm was unheard of by humans, but none the less it exists. Shinigami have crossed the access point between their world and ours, and delivered to humans the most "dangerous weapon of mass destruction in the history of mankind" [Ne