how do I buy it?
yes I'm in Japan!Good question, I do not see any prices on that site. You are in Japan?
Welcome to DIYGK.
I tried to get in touch, but I couldn't.
I sent an email to Haase a week ago, but I still haven't received a reply.Heres another site with the same catalog.
Are you looking for exact replacement parts?
Could something more readily available be used or modified to work?
Tell us more about your issues.
This is an automatic kart with only a rear brake; it is push-started.You have a shifter kart with front & Rear brakes, right? ~ If so: You might try contacting a company called Shark Shifter. They specialise in shifter race karts and might have rebuild-kits and/or new replacement master cylinders available for your application. https://sharkshifter.com/