This is the standard practice at many (but not all) Japanese companies with an overtime culture. "Service overtime" (サービス残業) -- uncompensated overtime -- is widely perceived to be abusive, and the abusiveness of this practice is deployed by defenders of the status quo as "We're not abusive; we paid every one of those 80 hours at time and a quarter."

It's priced into the expectations, literally -- my offer letter from my previous employer in Japan had two columns in it, the "formal offer" and the "offer assuming overtime pay[+]", with the number quoted at me being the total salary inclusive of their estimate of overtime. (30 hours of compensated overtime a month.)

(This was... ahem... an optimistic estimate.)