I have a serious concern about the translation! BC should be "more than 100 years ago", not exactly "100 years ago". The timeline reference to back cover has a "以上" which means "or more", while the timeline reference to BBS does NOT, as it's exactly 10 years.
It's a pretty big difference between "100 years ago" and "more than 100 years ago"!
BC's [...100年以上前の...] vs BBS's [...10年前の...]