Profesor being involved in WWII is interesting, well not like plenty of not so seemingly militaristic branches of science wasn't involved in some production lines of an actual weapons... plenty of companies that were suppliers still creates things used in them although meny had hard time adjusting after some market issues like recession...
Kei almost went all out on the store clerk, but the sake turning out to be just display is still kinda weird, sure it's there for a advertisement but wouldn't step inside a store with badly kept produce that spoils out in the sun.