theres a gatsby product meant to specifically remove other gatsby hair wax stuff, you can get it in japan in like Lawsons though i dont remember what it was called.
your hair bound to get destroyed if you dont wash it off properly or sleepign with the wax on (thats fucking gross imo wtf does that). thats why you should get hair treatment like once every half a year even though its kind of gay.
the best japanese hair wax imo is this brand called Spice. but for a small one cost like 40-50 imported (2,000 yen locally)
Best to worst Ive tried
Spice -> Uevo > Uno > Nakano Hair Styling > Gatsby
btw its way cheaper if you get gatsby off ebay than locally.