@WhiteWhaleJonas: Well, carbon fiber most likely. Bike have a "sweet spot" between 500 and 1000 €/$ for price efficiency, but above that the sky's the limit for ever so slight improvement in weight/stiffness.
@WhiteWhaleJonas: The tag say carbon so likely Carbon Fiber, which from what I can see from a quick google search seem to make for better vibration absorption and slightly lighter than typical aluminium frame.
There's probably some other things that make it cost more as well, but carbon fiber is part of it.
@WhiteWhaleJonas thats not that unusual. There are some bikes that are double that and even triple. Usually they are made up of titanium alloy or carbon fiber. My dad's Trek mountain bike cost him around 2k usd and that was closer to the bottom line.
FYI, Japan has very stringent rules on waste disposal and there are special taxes on oversized garbage, like home furnishings. I can understand that extra fee now.
@WhiteWhaleJonas My current bike was around 2K euros after we traded in an older one for a smal discount (tough its an electrical assist bike<- best translation i can think of.)
@Liquidxlax I think since Japan's garbage disposal)/recycling system has a particular order to it that he can't just put it in a trash bag. Even here in the US if I take a large item to dispose of to the dump myself they would still charge me a fee to deposit my trash.