Board Thread:General Discussion/@comment-5513888-20130903031231/@comment-124.106.137.86-20161021190818

Let me stomp on this theory.

http://angelbeats.wikia.com/wiki/Shiina

Read the very last trivia.

According to the 1st VN Shiina was there the longest (100 years)

The first successful heart transplant was on 1967

Otonashi looked like he was living in the modern world, even if it meant guessing that his life took place and died in the 80's or 90's

(no birthdate mentioned anywhere :c)

and considering this theory and Shiina being there for more than 100 years; that would mean the heart transplant happened before the year 1900! (his flashbacks don't look that old to me :/)

However if they were living in the year 2100+, your friend's theory will make sense but will not explain Shiina's culture shock.