I first got interested in the Japanese style leatherworkers knife after I caught something on YouTube showing the Olfa BTC-1 tool being used as a leatherworkers knife. It is available online but in the UK it is sold as a paint scraper (getting paint off windows) so I purchased mine from the Deluxe Trade Centre in Cheltenham for less than £10 with a pack of 3 extra blades BCB-1 being a few £.
The throw away blades make it ideal for those not used to sharpening tools, are of good quality, have two edges and do strop up well for longer life.
Olfa (being a Japanese company) made this tool as facsimile of a traditional leatherworker knife and even promotes this use on the blister pack it come in.
The knife os held like a dagger and used as a guillotine or pulled towards you.
When cutting curves it is tilted at an acute angle so that you are just using the far tip.