Rakuten, a Japan e-commerce and internet company, has led a $23m round of investment in US-based app developer, Slice. Slice uses the information buried in your email inbox to create fun and useful consumer applications and experiences. Slice is backed by DCM, Floodgate, Innovation Endeavors (Eric Schmidt), Lightspeed Venture Partners, NPD Group, Siguler Guff’s Russia Partners, as well as entrepreneurs Michael Birch and Rick Thompson. Launched in 2011, it also raised that year a series A round worth $9.4m.

The…