Less than a decade after stunning workers at his tech giant with an edict to learn English, billionaire Hiroshi Mikitani wants to do the same with computer programming.

Rakuten Inc. may soon expect its more than 17,000 employees to know how a computer compiles a program and understand the difference between a CPU and GPU (one is the brains of a PC, the other runs the graphics). Underpinning that is a mandatory, entry-level ability to code.

Mikitani, a trailblazer in Japan's internet economy, is considering this dramatic step as his e-commerce empire faces increasing pressure from the likes of Amazon.com Inc. It's an attempt to keep the skills of employees up to date and answer the question: Do you need to know programming to work in tech?