These so-called "Hawaiian" versions of the characters, which were produced in relatively small numbers, feature brighter colors than their Japanese counterparts, and therefore are popular among collectors both in Japan and abroad.
When the fad for soft-vinyl monsters began to fade in the mid-1970s, despite gimmicks such as sparker figures and magnets embedded in their palms (each of which included a tin friction-motor car), Bullmark began re-thinking the concept and released a series of soft-vinyl toys containing missile launchers, and other play gimmicks.
Bullmark co-founder Saburo Ishizuki explained in the afterword to the book Super #1 Robot that the diecast Mechagodzilla toy was "so popular that I could hardly keep up with demand... [so] I updated the look of the [other] monster characters with more robotic appearances and incorporated all-new action features."
The same year, Saburo Ishizuki took Bullmark's sales and marketing subsidiary Ark and turned it into a full-fledged toy manufacturer in its own right.
Ishizuki officially revived the brand as an independent company once again, with manufacturing and consulting support from Yuji Nishimura of M-1, in 2009.