JIS is defunct so I'm assuming 5260, but it would be nice if Chapman referenced it in their details
The JIS standard all together is still alive, its just the specific standard for the JIS screw hasn't been updated and been 'harmonized' with DIN 5260. The standard is still available, it just hasn't been updated or 'renewed'. Most have moved to 5260, because you can use it on both philips and JIS screws.
"Japan has stepped up efforts to harmonize JIS with international standards since the World Trade Organization (WTO)/Agreement on Technical Barriers to Trade (TBT) came into force in January 1995.
Consistency between JIS and International Standards
Total number of JIS 10,587 standards
Number of JIS with corresponding international standards 5,821 standards
JIS identical to international standards (IDT) 39%
JIS modified from international standards (MOD) 58%
JIS not equivalent to international standards (NEQ) 3%"
http://www.jisc.go.jp/eng/jis-act/index.html