The commentary suggests that the weapon is a Shanxi Type 17. This was one of the many, many clones of the Mauser C96 and/or Model 712 pistol to be found in warlord-era China, where guns of that type they were so popular, and so widely copied, that they had a distinct Chinese name, 盒子炮 ("box cannon"). The Type 17, unique to the forces of Shanxi warlord Yen Hsi-shan, is notable mainly for having been chambered in .45 ACP rather than the more typical 7.63mm Mauser or 9mm Parabellum cartridges (and for having been made in an actual factory, as opposed to the craft-built knockoffs that proliferated in China at the time).
Real Type 17s didn't have a detachable drum magazine, but I suppose it's not entirely impossible for some enterprising armorer to have built one. Lots of crazy stuff happened in the wild world of early-20th-century Chinese firearms.
(As an aside regarding Inazuma having one here: while the Japanese armed forces aren't known to have used any C96-type pistol officially, there would still have been hundreds of thousands if not millions of them around at the time of the Sino-Japanese Wars--although only about 8,500 actual Type 17s were ever made.)